View Article Online View Journal NJC New Journal of Chemistry Accepted Manuscript A journal for new directions in chemistry This article can be cited before page numbers have been issued, to do this please use: A. Pinto, G. Hernandez, R. Gavara, E. Aguiló, A. J. Moro, G. Aullon, M. Malfois, J. C. C. Lima and L. Rodriguez, New J. Chem., 2019, DOI: 10.1039/C9NJ00469F. Volume 40 Number 1 January 2016 Pages 1–846 This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. NJC New Journal of Chemistry A journal for new directions in chemistry Accepted Manuscripts are published online shortly after www.rsc.org/njc acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the author guidelines. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s ISSN 1144-0546 standard Terms & Conditions and the ethical guidelines, outlined PAPER in our author and reviewer resource centre, still apply. In no Jason B. Benedict et al. The role of atropisomers on the photo-reactivity and fatigue of diarylethene-based metal–organic frameworks event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. rsc.li/njc Page 1 of 30 New Journal of Chemistry 1 2 3 Supramolecular tripodal Au(I) assemblies in View Article Online DOI: 10.1039/C9NJ00469F 4 5 6 7 water. Interactions with pyrene fluorescent 8 9 probe. New Journal of Chemistry Accepted Manuscript 10 11 12 13 Andrea Pinto,a,b Guillem Hernández,a Raquel Gavara,a Elisabet Aguiló,a Artur J. Moro,c Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 Gabriel Aullón,a Marc Malfois,d João Carlos Lima,c Laura Rodríguez.a,b,* 15 16 a 17 Departament de Química Inorgànica i Orgànica. Secció de Química Inorgànica. 18 Universitat de Barcelona, Martí i Franquès 1-11, 08028 Barcelona, Spain. Tel.: +34 19 20 934039130. e-mail: laura.rodriguez@qi.ub.es 21 b Institut de Nanociència i Nanotecnologia (IN2UB). Universitat de Barcelona, 22 23 24 08028 Barcelona (Spain) 25 c LAQV-REQUIMTE, Departamento de Química, Universidade Nova de Lisboa, 26 27 Monte de Caparica, Portugal. 28 d ALBA Synchrotron Light Laboratory (CELLS), Carrer de la Llum 2−26, 08290 29 30 31 Cerdanyola del Vallès, Barcelona, Spain 32 33 34 35 Dedicated to Prof. Ernesto Carmona on occasion of his 70th anniversary. 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 1 New Journal of Chemistry Page 2 of 30 1 2 3 4 Abstract View Article Online DOI: 10.1039/C9NJ00469F 5 6 The synthesis of three gold(I) tripodal complexes derived from tripropargylamine and 7 8 containing the water soluble phosphines PTA (1, 3,5-triaza-7-phosphaadamantane), 9 DAPTA (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) and TPPTS New Journal of Chemistry Accepted Manuscript 10 11 (triphenylphosfine-3,3’,3’’-trisulfonic acid trisodium salt) is here described. The three 12 13 complexes are observed to give rise to the formation of supramolecular aggregates in Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 water and very long fibers. This property has been analyzed by means of 1H-NMR 16 spectroscopy at different concentrations and SAXS. The results point out the important 17 18 role of the phosphine moieties as the main enthalpic or entropic contribution in the 19 20 resulting Gibbs energy of aggregates formation. 21 22 The tripodal structure of the three complexes together with the presence of gold(I) 23 24 atoms make them ideal candidates to interact with hydrophobic molecules also in water. 25 26 For this, the interaction with pyrene in this solvent has been evaluated with successful 27 results in all three complexes. The highest association constant corresponds to 2 as the 28 29 host. DFT studies indicates the location of pyrene in the tripodal cavity as the most 30 31 stable conformation. The interaction with pyrene has been additionally studied within 32 cholate hydrogel matrixes pointing out the stability of the resulting host:guest adducts in 33 34 the different medium. 35 36 37 38 39 40 41 42 Keywords: gold(I), tripodal, hydrogels, luminescence, pyrene 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 Page 3 of 30 New Journal of Chemistry 1 2 3 4 Introduction View Article Online DOI: 10.1039/C9NJ00469F 5 6 Nature, especially in biological systems, has an extraordinary ability to develop 7 8 complex and functional molecular assemblies employing reversible non-covalent 9 interactions.1 These examples from Nature have inspired chemists over the past several New Journal of Chemistry Accepted Manuscript 10 11 years to develop synthetic protocols to obtain complex assemblies employing 12 13 supramolecular interactions such as hydrophobic forces, hydrogen-bonding, transition Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 metal coordination, and gels formation among others.2-6 These structures are worthy 16 candidates to be involved in processes such as catalysis,7-9 sensing,10-13 artificial photo- 17 18 capturing systems14 or encapsulation among others.15 Container (encapsulating) 19 20 architectures can encage guest molecules within a confined space, dynamically 21 harnessing multiple non-covalent interactions. In particular, encapsulation of planar 22 23 hydrophobic molecules is an important strategy to remove from water pollutants with 24 25 mutagenic and/or carcinogenic effects.16,17 However, up to date the number of precedent 26 27 examples of supramolecular metallocapsules that exhibit sufficient structural flexibility 28 to adapt diverse substrates by adjusting the cavity size are scarce.18-21, The majority of 29 30 examples are pure organic macrocyclic compounds such as calix[n]arenes, 31 32 cyclodextrins, cucurbit[6]urils which can be water soluble and possess a hydrophobic 33 34 cavity compared to water.22-25 Less examples are described with metallocavitands acting 35 as hosts.26,27 36 37 38 Furthermore, to the best of our knowledge, there are not found in the literature 39 reports based on gold(I) systems as hosts for the molecular recognition of arenes in 40 41 water, These kind of structures present the advantage of having additional points of 42 43 interactions (e.g. Au···, C-H···Au, N-H···Au)28,29 that can improve their sensing 44 45 process. Additionally, they can be designed to be obtained in short synthetic routes (1-2 46 steps) with moderate-high yields. An interesting way to proceed is based on the 47 48 synthesis of tripodal gold(I) structures able to detect guest molecules within their open 49 50 cavities. Although some investigations have been done regarding this for the 51 52 recognition of cations in organic solvents,30,31 as far as we know, there are not reports 53 for the recognition of aromatic molecules in water. Taking into consideration all of this, 54 55 we present herein the synthesis and characterization of three tripodal gold(I) complexes 56 57 that are observed to self-assemble in aqueous medium giving rise to the formation of 58 aggregates and very long fibers. The supramolecular structures contain hydrophobic 59 60 3 New Journal of Chemistry Page 4 of 30 1 2 3 (gold atoms atoms and alkynyl groups) and hydrophilic moieties (located at theView Article Online DOI: 10.1039/C9NJ00469F 4 5 phosphines). Previous work reported by us has been mainly based on linear 6 7 mononuclear compounds containing aromatic chromophores that can improve the self- 8 9 assembly process by the presence of    interactions.3,5,11,12,29 In this work, we can New Journal of Chemistry Accepted Manuscript 10 demonstrate that the absence of this type of interactions, based on the presence of 11 12 aromatic chromophores, does not prevent intermolecular contacts and aggregation 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 leading to the formation of very long fibers. The simplicity of the present molecules are 15 particularly important since it can be demonstrated that only Au(I) and probably some 16 17 hydrogen bonds coming from phosphine units are necessary in these supramolecular 18 19 assemblies. 20 21 The ability of these large supramolecular hydrophobic aggregates to act as 22 23 binding sites is successfully proved using pyrene as probe in aqueous medium. The 24 25 choice of pyrene is based on its efficient fluorescence which has proved to be a useful 26 tool for measuring hydrophobic environments as well as complex formation in 27 28 host:guest processes.23, 32-35 29 30 31 The resulting weak host:guest interactions have been also tested in metal 32 cholate hydrogels in order to compare their stability and to analyse the role gold(I) 33 34 within this organic matrix.36,37 Although a variety of metal cholates were shown to form 35 36 hydrogels, to the best of our knowledge there are not examples of organometallic 37 complexes included within this supramolecular hydrogelator structure. 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 4 Page 5 of 30 New Journal of Chemistry 1 2 3 View Article Online DOI: 10.1039/C9NJ00469F 4 5 Results and Discussion 6 7 8 Synthesis and Characterization 9 New Journal of Chemistry Accepted Manuscript 10 The trinuclear phosphine Au(I) acetylides 1-3 were prepared by slight modifications on 11 12 a previously reported method,38 by treatment of [AuCl(PR3)] (PR3 corresponding to the 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 water-soluble phosphines PTA, DAPTA and TPPTS) with terminal tripropargylamine 15 in the presence of KOH base in methanol (Scheme 1). The three different phosphines 16 17 (two neutral and one anionic) were carefully chosen due to the increasing degree of 18 19 solubility in water (PTA < DAPTA < TPTTS) in order to study the potential correlation 20 21 between the global solubility of the complexes in water and the observed aggregation 22 motifs. R 3P 23 24 CH2Cl2 / MeOH or MeOH Au R 3P Au Cl 25 26 tripropargylamine R 3P PR3 27 Au Au 28 KOH 29 N 30 31 O 32 N N 33 P N P N NaO3S P SO3Na 34 PR3 = 35 N N 36 O SO3Na 37 38 1 2 3 39 40 41 Scheme 1. Synthesis of complexes 1-3. 42 43 44 45 46 The reaction was performed in CH2Cl2/MeOH (in the case of 1 and 2) or MeOH (in the 47 48 case of 3 in order to improve the solubility of the AuCl(PR3) reactant) and the solution 49 50 reaction was protected from light with aluminum foil and stirred at room temperature 51 for ca. 3h. The resulting compounds were obtained in pure form after filtration through 52 53 Celite and recrystallization with dichloromethane/hexane. 54 55 31P 56 NMR spectra display single resonances at -40.1 ppm (1), -13.9 (2) and 42.5 ppm (3) 57 in accordance with P-donor coordination to the metal center. 1H NMR shows the 58 59 disappearance of the signal related to the tripropargylamine terminal proton at ca. 2.3 60 5 New Journal of Chemistry Page 6 of 30 1 2 3 ppm, as the main indication of the successful formation of the products. Additionally,View Article Online DOI: 10.1039/C9NJ00469F 4 5 the methylene proton of the N-CH2-C≡C moiety (ca. 3.50 ppm) appears as a singlet 6 7 instead of the doublet observed in the propargylamine starting material, due to the 8 coupling with the terminal alkynyl proton (Figures 1 and S1-S5). This methylene proton 9 New Journal of Chemistry Accepted Manuscript 10 becomes much broader and almost disappear in the case of 1 (containing the less 11 12 soluble phosphine) in D2O (see Figure S6), being an indicative of the formation of 13 supramolecular aggregates in this solvent (see Aggregation behaviour Section). Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 Figure 1. 1H-NMR spectrum of 1 in CDCl3. 39 40 41 42 Infrared spectra show additional evidence of the successful formation of the products 43 44 due to the disappearance of the signal related to the terminal alkynyl at 3100-3000 cm-1 45 46 in the final products. Mass spectra confirmed in all cases the correct formation of the 47 products with the corresponding m/z [M+H+] peaks detection in 1 and 2 and [M- 7 Na++ 48 49 4H+ + 3 H2O]3- in 3. 50 51 52 53 54 Aggregation behaviour 55 1H-NMR data recorded at different concentrations and times are a direct evidence of the 56 57 58 formation of aggregates. There is a linear correlation between the area of the phosphine 59 protons and concentration in fresh solutions (Figures S7-8). Additionally, as observed in 60 6 Page 7 of 30 New Journal of Chemistry 1 2 3 Figure 2, there is a slight upfield shift of the N-CH2-N phosphine protons at ca.DOI: 4.810.1039/C9NJ00469F ppmView Article Online 4 5 (red arrow) upon aggregation with time, being a direct indication of the involvement of 6 7 this unit in the formation of the supramolecular structures. This shift is accompanied 8 with a decrease on the phosphine protons integration with time, due to the expected 9 New Journal of Chemistry Accepted Manuscript 10 broadening of the aggregated protons, and the observation of precipitate formation in 11 12 the solution. 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 Figure 2. 1H NMR spectra of 2 at 2.6·10-3M concentration in D2O recorded in freshly 42 prepared solutions and after 2, 5 and 7 days (left); Variation on the area of the more 43 44 downfield shifted phosphine proton upon aggregation with time (right). 45 46 47 48 49 The size and shape of the aggregates were measured by SAXS at different 50 51 concentrations (1·10-4 M, 5·10-5 M, 1·10-5 M and 5·10-6 M) in water, at different 52 temperatures (from 20 ºC to 40 ºC in a 5 ºC gradient) and one week after their 53 54 preparation in order to favor aggregation. The low-resolution structures were 55 56 reconstructed ab initio from the scattering patterns using the DAMMIN program39 (see 57 some examples in Figures 3 and S9-11). Smaller size aggregates were recorded at 58 59 higher concentrations, mainly in the case of the more water soluble complexes 2 and 3. 60 7 New Journal of Chemistry Page 8 of 30 1 2 3 This can be due to the precipitation of the complexes in the medium when increasing View Article Online DOI: 10.1039/C9NJ00469F 4 5 concentration, giving rise to larger structures unable to be detected by SAXS. This is in 6 7 agreement with the observed fibers’ formation (see below optical microscopy 8 characterization) and the aggregation detected by NMR for one-week-old solutions 9 New Journal of Chemistry Accepted Manuscript 10 (Figure 2). This behavior was already observed recently for other gold(I) complexes that 11 12 aggregate in water.12 Higher concentrations, in the order of ca. 10-3 M as those used for 13 NMR experiments, were not possible to be measured by SAXS precluding a strict Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 comparison between these two techniques. 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 Figure 3. DAMMIN low-resolution structures reconstructed from SAXS patterns for 50 1·10−4 M (left) and 1·10−5 M (right) solutions of 1 (top), 2 (middle) and 3 (bottom) in 51 52 water. 53 54 55 In general, temperature does not affect substantially the aggregates’ size. Nevertheless, 56 in some cases (compound 1 at 1·10-5 M and compounds 2 and 3 at 5·10-5 M 57 58 concentrations) there is a variation around 100 Å (large enough to discard as error 59 60 8 Page 9 of 30 New Journal of Chemistry 1 2 3 deviation). While an increase on the size is measured in complex 1 (280 Å at DOI: 20ºC and View Article Online 10.1039/C9NJ00469F 4 5 370 Å at 35 ºC), a decrease can be detected for 2 and 3 (340-300 Å at 20ºC and 230-200 6 7 Å at 35 ºC). This may be attributed to a more hydrophobic character of 1, being 8 hydrophobic interactions more favored at higher temperatures. In the case of 2 and 3, it 9 New Journal of Chemistry Accepted Manuscript 10 is expected that hydrogen bonding intermolecular contacts, due to the presence of 11 12 oxygen atoms in their phosphine ligands, are disfavored at higher temperatures,40 giving 13 rise to smaller structures. Similar behavior was previously detected by us with PTA and Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 DAPTA gold(I) derivatives where the entropic factor (due to the release of water 16 17 molecules upon aggregation) was the driving force for the aggregates’ formation in the 18 19 first case (PTA, and in our case complex 1). This was the most important contribution 20 21 on the calculated negative Gibbs energy for the aggregation process. On the contrary, 22 enthalpic factors become more important for DAPTA complex 2 (and extensively for 23 24 complex 3) where additional hydrogen bonding contacts may be established between 25 26 the oxygen atoms of the phosphine and the solvent.41 27 28 Optical microscopy images show that the resulting translucent empty fibers can grow up 29 30 to hundreds of micrometers length and ca. 5 micrometers width (Figure 4). At lower 31 32 concentrations the fibers are thinner and cleaner as depicted in Figures 4 and S12, 33 building up to the formation of well-defined fibrillary self-assembled structures. 34 35 36 37 38 39 40 41 42 43 44 45 46 Figure 4. Optical microscopy images of fibers obtained from 1·10-5 M aqueous 47 48 solutions of 1 (A), 2 (B) and 3 (C). 100x magnification. 49 50 51 52 53 Supramolecular interactions with pyrene 54 55 The tripodal nature and the presence of gold(I) atoms in compounds 1-3 make them 56 57 ideal candidates to be used as hosts by using the hydrophobic counterparts for the 58 interaction with aromatic (and hydrophobic) guests in water. 59 60 9 New Journal of Chemistry Page 10 of 30 1 2 3 Absorption differential spectra of 1·10-5 M solution of pyrene in the presence of View Article Online DOI: 10.1039/C9NJ00469F 4 5 increasing amounts of host display no significant variations. It is worth to mention an 6 7 increase on the light dispersion probably due to the presence of host aggregates in water 8 that can interact with pyrene molecules (see below emission titrations). This dispersion 9 New Journal of Chemistry Accepted Manuscript 10 of light is less observed in the presence of complex 3 due to its better solubility in water 11 12 (Figures S13-15). The calculated pyrene solubility in water based on absorption spectra 13 (Figures S13-15) and its reported molar absorption coefficient at 336 nm (32.500 M- Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 1·cm-1, 42) is 0.77 m, which is in agreement with the literature. 43 This means that this is 16 17 the only amount of pyrene solubilized in water from the 1·10-5 M solution prepared. The 18 19 rest, is expected to be involved in the interaction process with gold(I) tripodal 20 21 complexes giving rise to larger adducts that are affecting the dispersion baseline. In this 22 way, free pyrene is removed from aqueous solution due to its solubilization by its 23 24 interaction with the hydrophobic gold(I) host systems, giving rise to the formation of 25 26 small aggregates that may present a very small absorptivity coefficient as indicated by 27 28 the small increase of the absorption upon complex formation. 29 30 Emission titration data display a decrease on the pyrene intensity in the presence of the 31 32 tripodal complexes (Figures S16-18). The recorded fluorescence quenching of pyrene 33 observed from the interaction with gold(I) receptors follows the same behaviour 34 35 previously shown in other supramolecular systems containing hydrophobic inner 36 37 cavities such as by calix[4]arene and calix[4]resorcinarenes.44 Thus, it should be 38 39 expected a partially supramolecular host···guest adduct formation between the pyrene 40 and the gold(I) structures giving rise to the formation of non-emissive Au··· and/or C- 41 42 H··· assemblies,45 present in very small dispersive state in solution (according to 43 44 absorption scattering) that are also quenching the emission of the free pyrene solubilized 45 46 in water. The recorded decrease on intensity follows the trend 2 > 3 > 1, as an indication 47 of the expected more efficient host:guest contact in the presence of better water soluble 48 49 gold(I) hosts 2 and 3. Additionally, the plot of the intensity at the emission maxima 50 51 versus concentration indicates a change on the slope at one equivalent of gold(I) 52 53 complex, in agreement with 1:1 interaction. 54 55 Similar titrations carried out in the absence of oxygen do not display the presence of 56 57 pyrene phosphorescence as a consequence of a triplet population by intersystem 58 crossing due to heavy atom effect.46 Additionally, the band at 473 nm corresponding to 59 60 10 Page 11 of 30 New Journal of Chemistry 1 2 3 the pyrene excimer formation is not observed in the fluorescence emissionDOI:spectra View Article Online 10.1039/C9NJ00469F 4 5 neither in the presence nor in the absence of the receptor. 6 7 31P NMR titrations of gold complexes in the presence of 0.5, 1 and 2 equivalents of 8 9 pyrene display a ca. 0.5 ppm upfield shift of the phosphorous signal upon interaction New Journal of Chemistry Accepted Manuscript 10 11 with the aromatic molecule and this shift is maintained constant from 1 equivalent, 12 13 supporting the 1:1 complex formation (Figure 5). This means that pyrene molecule is Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 clearly affecting the chemical vicinity of the phosphine, although no direct coordination 15 16 is expected due to the small chemical shift variations. The first and larger effect 17 18 observed in the presence of 0.5 equivalents of pyrene indicates the formation of a quite 19 stable intermediate corresponding to the 2:1 (gold complex: pyrene) adduct which could 20 21 be detected by mass spectrometry with the corresponding M + H+- 4 Au-DAPTA + 22 23 CH2Cl2 + 5 H2O peak at m/z 1490.1.2 (being M = 2 * (2) + pyrene). The formation of 24 25 this type of pyrene 2:1 adducts was previously observed with organic capsules.47 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 Figure 5. 31P{1H} NMR spectra of 2 in D2O in the absence (left) and in the presence of 54 55 increasing amounts of pyrene dissolved in CD3OD. 56 57 58 59 60 11 New Journal of Chemistry Page 12 of 30 1 2 3 The size of the resulting host:guest supramolecular assemblies depends on the DOI: solubilityView Article Online 10.1039/C9NJ00469F 4 5 in water of the complexes as evidenced by SAXS. Thus, the resulting 1:1 adduct from 6 7 1·10-5 M aqueous solution of 1 in the presence of one equivalent of pyrene increases the 8 size in ca. 50 % while in the case of more water soluble hosts, 2 and 3, a decrease on the 9 New Journal of Chemistry Accepted Manuscript 10 size (ca. 15 and 40 %) is evidenced by this technique (see Figure S19). That means that 11 12 host:guest interactions not only affects the aggregates’ formation but also the 13 intermolecular supramolecular arrangement. Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 Since the fluorescence spectrum of pyrene is sensitive to changes on its 17 18 microenvironment, this technique is useful in probing the encapsulation and interaction 19 of aromatic molecules within the inner cavities of the tripodal complexes.48 This is 20 21 detected by changes on the relative intensity between the first and the third pyrene 22 23 emission peaks (I1/I3) which is known to be sensitive to the polarity of the 24 25 microenvironment where it is placed.49 The reasons for these observations have been 26 attributed to excited state interaction of the molecule with the surrounding solvent and 27 28 solvent reorientation around the excited state dipole.50,51 29 30 The I1/I3 ratio was found to vary with the concentration of the tripodal complexes in 31 32 water (Figures 6 and S20-22). The decrease in I1/I3 in emission spectra at a higher 33 34 concentration of gold complexes, indicates the partitioning of pyrene from an aqueous 35 36 environment to a more hydrophobic location (Table 1 left). As expected, the recorded 37 changes are slightly higher in the case of 1, containing the most hydrophobic phosphine, 38 39 PTA. The variations on the I1/I3 ratio in the presence of pyrene recorded in all cases are 40 41 well fitted by a binding isotherm for 1:1 complexation and allowed the determination of 42 43 the association constants for the formation of the adducts (Table 2). 44 45 6 46 6 3.0x10 3x10 47 48 49 I372nm corrected 6 2.5x10 50 51 6 52 2x10 53 I (a.u.) 6 2.0x10 54 55 56 57 6 1x10 0 1 2 3 4 5 58 nº equivalents of 2 59 60 12 0 400 500 600 Wavelength (nm) Page 13 of 30 New Journal of Chemistry 1 2 3 View Article Online DOI: 10.1039/C9NJ00469F 4 5 6 7 8 9 New Journal of Chemistry Accepted Manuscript 10 11 12 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 17 18 19 20 21 22 Figure 6. Emission spectra of a 1·10-5M solution of pyrene in the presence of increasing 23 24 amounts of 2. Inset: plot of the variation of I372 nm vs number of equivalents of host. 25 26 27 28 29 Table 1. Calculated I1/I3 ratio as indication of pyrene polarity environment. 30 31 32 Compound I1/I3 ratio Sample I1/I3 ratio 33 pyrene 1.89 pyrene @ cholate 0.86 34 pyrene : 1 1.65 pyrene : 1@cholate 1.10 35 pyrene : 2 1.72 pyrene : 2@cholate 1.12 36 37 pyrene : 3 1.71 pyrene : 3@cholate 0.87 38 39 40 Table 2. Kass values (logK) of the formation of adducts between gold(I) complexes (1- 41 42 3) and pyrene. Estimated error: 4% 43 44 Compound logK 45 46 1 5.3 47 48 2 5.8 49 50 3 5.1 51 52 53 54 As stated above, the occurrence of C-H··· and Au···H-C interactions can be related to 55 56 the host:guest adduct formation, since this kind of contacts have been previously 57 detected in the X-ray crystal structures of gold(I) alkynyl complexes with arenes.28 This 58 59 could be the main reason for the higher Kass value retrieved for 2, due to the possible 60 13 New Journal of Chemistry Page 14 of 30 1 2 3 presence of additional C-H··· interactions between the acetyl moieties andDOI:pyrene. View Article Online 10.1039/C9NJ00469F 4 5 Additionally, the lack of significant quenching observed in the case of 1 let us affirm 6 7 that Au···, C-H··· or N-H··· adducts are not producing quenching while the oxygen 8 9 electron pairs coming from phosphines in 2 and 3 may be directly related with this New Journal of Chemistry Accepted Manuscript 10 phenomena. 11 12 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 Theoretical Calculations 16 17 18 In an attempt to understand the structure of pyrene@adducts, we have performed 19 theoretical study using DFT calculations with complex 1 as a model. The different 20 21 molecular geometries have been optimized in order to evaluate their relative stabilities 22 23 and to determinate the nature of pyrene···1 interactions. These modelled geometries are 24 shown in the Figure 7, namely by a capital letter. 25 26 27 The structure of the trinuclear gold complex provides a feasibility to incorporate a 28 29 pyrene molecule within the cavity. In consequence, model A that contains pyrene 30 between the planes of 1 results as the most stable structure. The molecular analysis of 31 32 this geometry shows short C-H group of the phosphine ligand and aromatic carbon 33 34 atoms having distances until 2.9 Å indicating the presence of C-H··· interactions. 35 36 Nevertheless, pyrene can rotate 90º keeping molecular plane as B, and it is destabilized 37 by only 0.75 kcal/mol, probably by increasing of phosphine···pyrene distances. In both 38 39 A and B models, our study suggests that the ratio between pyrene and 1 would be 1:1. 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 14 Page 15 of 30 New Journal of Chemistry 1 2 3 View Article Online DOI: 10.1039/C9NJ00469F 4 5 6 7 8 9 New Journal of Chemistry Accepted Manuscript 10 11 12 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 Figure 7. Full optimized structures for pyrene@1 adducts, together with the relative 43 stability. Energies are provided in kcal/mol, taken the most stable as reference (A). 44 45 46 47 48 On the other hand, we have considered the possibility to leave the pyrene outside of 49 50 trinuclear gold compound. In this case, two models have been computed, D and E, 51 having different rotation of pyrene to interact with trigold compound. The final 52 53 geometries show interactions between C-H and C≡C groups of pyrene and alkynyl 54 55 fragments, respectively, even that initial calculations were started to present C-H···Au 56 57 contacts. In D, these non-bonded distances are about 2.9 and 3.5 Å, respectively, 58 indicating that former is the driving force to generate the adduct. The relative stability 59 60 15 New Journal of Chemistry Page 16 of 30 1 2 3 of D is only 1.27 kcal/mol above A and it could be accessible, but a second pyrene View Article Online DOI: 10.1039/C9NJ00469F 4 5 could be added on following face of trigold compound being in disagreement with 1:1 6 7 ratio. Analogously, E presents larger contacts that D resulting more unfavored. 8 Moreover, our study also reveals that interactions between phosphine and pyrene of C, 9 New Journal of Chemistry Accepted Manuscript 10 having largest C-H··· interactions, is less preferred of the five calculated models, and 11 12 it can be rejected. 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 17 Stability in cholate gels 18 19 Gold···pyrene interactions were also analysed after the inclusion of the gold(I) 20 21 complexes within cholate hydrogels (see Figure S23), synthesized following the 22 23 literature method,52 in order to get some additional information about the stability of 24 this interaction in different environments. This matrix has been very well studied by 25 26 Maitra’s research group together with the effect of metal cations in the gelation 27 28 process.52 The high stability, bio-compatibility and lack of toxicity observed in these 29 30 studies encouraged us to use it to include our systems and analyse if the stability of our 31 supramolecular assemblies is also maintained in this thicker environment. For this goal, 32 33 the formation of this organic/organometallic matrices was carried out by the 34 35 introduction of: i) gold(I) complexes; ii) pyrene; and iii) both host and guest molecules 36 in 1:1 ratio. 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 16 Page 17 of 30 New Journal of Chemistry 1 2 3 The presence of small aggregates (due to the presence of gold complexes) located on the View Article Online DOI: 10.1039/C9NJ00469F 4 5 cholate fibers are clearly observed in the case of 1 and 2 (Figure 8 B-C). A particular 6 7 case was the inclusion of the negatively charged complex 3. As can be seen in Figure 8 8D, this compound is directly taking part of the cholate matrix due to its ionic nature 9 New Journal of Chemistry Accepted Manuscript 10 and no aggregates are deposited onto the cholate fibers. 11 12 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 Figure 8. Transmission electron microscopy images of dried samples of cholate 40 41 hydrogel (A); 1 @ cholate (B); 2 @ cholate (C) and 3 @ cholate (D). 42 43 44 45 46 Divalent cation cholate hydrogels are known to show liquid crystalline schlieren 47 48 textures52 when the wet gels are investigated in a polarizing optical microscope. As 49 previously observed, the xerogels (dried gels) did not show any birefringence 50 51 suggesting that the liquid crystalline behaviour in the wet hydrogels arise from the 52 53 anisotropy created by the immobilized water inside the self-assembled nanofibres. 54 55 These liquid crystalline properties of the metal cholate hydrogels show that they have a 56 positional long-range order which is not always true for molecular gels as they might 57 58 59 60 17 New Journal of Chemistry Page 18 of 30 1 2 3 have isotropic phases without any long-range order.53 These properties are maintained View Article Online DOI: 10.1039/C9NJ00469F 4 5 in the presence of gold(I) complexes (Figure S24). 6 7 Analogous organic/organometallic hybrid systems were obtained in the presence of one 8 9 equivalent of pyrene. The resulting optical and electronic microscopy images indicate New Journal of Chemistry Accepted Manuscript 10 11 the presence of both gold(I) complexes and pyrene within the cholate matrix. Inspection 12 13 of Figure S25 shows the presence of larger and more brilliant aggregates in the case of 1 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 and 2 although it is not so clear with 3 in agreement with the presence of this complex 15 16 within the cholate structure and not as agglomerates located on the fibers. Inspection of 17 18 the samples by TEM shows the presence of white plates, assigned to pyrene deposition 19 (Figure 9), located above the darker organometallic aggregates. It should be noted that 20 21 these observations must be performed at very low electron beam irradiation since, as 22 23 previously observed in other gold(I) alkynyl complexes, the formation of Au(0) 24 25 nanoparticles is induced by electrons54 (Figure S26). 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 Figure 9. TEM image of 2 : pyrene @ cholate. White plates (orange arrows) are 45 indicative of pyrene and black agglomerates (blue arrows) indicate 2-supramolecular 46 47 structures. 48 49 50 51 52 The recorded emission spectra of pyrene@cholate samples in the presence and in the 53 54 absence of 1-3 are a direct evidence of pyrene:gold interaction in the case of the neutral 55 complexes 1 and 2 as it is displayed by the changes on the I1/I3 ratio (Figure 10 and 56 57 Table 1 right) which seem to be slightly favoured in the presence of 1 due to its higher 58 59 hydrophobic character. 60 18 Page 19 of 30 New Journal of Chemistry 1 2 3 View Article Online DOI: 10.1039/C9NJ00469F 4 5 6 7 7 2.5x10 8 pyrene 9 7 2.0x10 1 + pyrene New Journal of Chemistry Accepted Manuscript 10 2 + pyrene 11 3 + pyrene 12 7 1.5x10 I (a.u.) 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 7 15 1.0x10 16 17 6 5.0x10 18 19 20 0.0 21 400 500 600 22 Wavelength (nm) 23 24 25 Figure 10. Emission spectra of pyrene@cholate, pyrene : 1@cholate, pyrene : 26 2@cholate and pyrene : 3@cholate. 27 28 29 30 The lack of effect observed for pyrene : 3@cholate is due to the ionic nature of this 31 32 complex included within the organic matrix precluding the interaction with the arene. 33 Additionally, and on the basis of literature data,55 changes in signal intensity or shifts in 34 35 the maxima of the spectrum could indicate complex formation. The decrease on the 36 37 recorded intensity of pyrene in the presence of 1 and 2 is a further indication of the 38 successful 1 / 2-pyrene adduct formation within the organic matrix. 39 40 41 Thus, tripodal gold(I) complexes have been demonstrated to be good candidates to act 42 43 as supramolecular hosts of organic molecules in water taking into consideration the 44 hydrophobic character of both gold(I) atoms and organic counterpart. These interactions 45 46 can be reinforced by the possible establishment of Au··· interactions additionally to 47 48 classical weak contacts and they are stable with their introduction into cholate organic 49 50 matrixes as solid supports in the case of neutral complexes that do not compete with the 51 matrix hydrogelation process. 52 53 54 55 56 57 58 59 60 19 New Journal of Chemistry Page 20 of 30 1 2 3 4 Conclusions View Article Online DOI: 10.1039/C9NJ00469F 5 6 The formation of large supramolecular assemblies in gold(I) tripodal derivatives is 7 8 favoured by concentration and time. The resulting aggregates’ formation depends on the 9 solubility in water of the phosphine being an enthalpic (for 2 and 3) or entropic (in the New Journal of Chemistry Accepted Manuscript 10 11 case of 1) driving process. Entropic factors are ascribed to the release of water 12 13 molecules upon aggregation (hydrophobic effect) in complex 1. This behaviour is also Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 observed with the complex containing the highly water soluble and negatively charged 16 trisulphonated phosphine TPPTS, although longer times are required. 17 18 1H 19 NMR spectroscopy together with SAXS and microscopic techniques (OM and TEM) 20 give information about the formation of the aggregates and their sizes. SAXS and 21 22 microscopic techniques are important for the analysis of their shape. 23 24 25 The presence of hydrophilic groups (phosphines) and hydrophobic moieties (organic 26 part and gold centers) within the same molecules make these complexes ideal 27 28 candidates to interact with aromatic molecules within the supramolecular structure as 29 30 has been demonstrated in the case of pyrene. DFT studies suports the formation of 31 gold:pyrene adducts with the most stable expected conformation with the aromatic 32 33 moiety within the tripodal cavity. 34 35 36 The interaction with pyrene is produced both in water and in cholate gelators being 37 stable in both cases for neutral derivatives while the presence of negative charges in the 38 39 TPPTS phosphine in 3 makes the compound to become an integral part of the cholate 40 41 fibrillar network. Additionally, the higher solubility in water of DAPTA (2) compared 42 to PTA (1) gives rise to stronger adduct formation with pyrene. 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 20 Page 21 of 30 New Journal of Chemistry 1 2 3 4 Experimental Section View Article Online DOI: 10.1039/C9NJ00469F 5 6 General procedures. All manipulations have been performed under prepurified N2 7 8 atmosphere using Schlenk techniques. All solvents were distilled from appropriated 9 drying agents. MilliQ water quality was used for the preparation of the corresponding New Journal of Chemistry Accepted Manuscript 10 11 solutions. The pH of the solutions was maintained neutral in order to ensure the neutral 12 13 state of the amine groups. Deuterated solvents were obtained from Aldrich and were Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 used as received except chloroform that was treated with alumina and under nitrogen 16 atmosphere. Commercial reagents 1,3,5-triaza-7-phosphaadamantane (PTA, Aldrich, 17 18 97%), 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA, Aldrich, 19 20 97%), triphenylphosfine-3,3’,3’’-trisulfonic acid trisodium salt (TPPTS, Aldrich, 95%) 21 22 have been used as received, Literature methods were used to prepare [AuCl(PR’3)] 23 (PR’3 = PTA,56 DAPTA.56 24 25 26 Physical Measurements. IR spectra were recorded as KBr disk with IR-Avatar 330 FT- 27 28 IR Thermo Nicolet. 1H NMR ((TMS)=0.00) and 31P{1H} NMR spectra were recorded 29 with a Varian Mercury 400 and Bruker 400. 1H NMR studies at different concentrations 30 31 performed to evaluate aggregation process have been performed using long relaxation 32 33 delays of 5-10 times T1 and the differences of integration with concentration have been 34 strickly evaluation with respect to TSP used as reference. ElectroSpray-Mass Spectra 35 36 (+/-) were measured with a Fision VG Quatro spectrophotometer. The water used for 37 38 the solutions of absorption and emission measurements was obtained through a 39 40 Milliport Ven Filter MPK01. Absorption spectra were recorded with UV-visible Varian 41 Cary 100 Bio spectrophotometer. Emission spectra were recorded with Nanolog-Horiba 42 43 Jobin Yvon spectrofluorimeter. Optical micrographs were recorded with a Leica 44 45 DM1000LED and TEM images were recorded with a Tecnai G2 Spirit microscope. The 46 47 measurements were acquired using a carbon TEM support films on cooper where the 48 cholate hydrogels were deposited the day before and dried during 24h. 49 50 51 Small angle X-ray scattering 52 53 SAXS data have been performed on the NCD-SWEET beamline at the synchrotron 54 55 ALBA at 12.4 keV and the distance sample/detector was 6.2m to cover the range of 56 momentum transfer 0.028 < q <2.56 nm-1. The data were collected on a Pilatus3S 1M 57 58 detector with a pixel size of 172.0x172.0m2. The exposure time was 30s. The q-axis 59 60 21 New Journal of Chemistry Page 22 of 30 1 2 3 calibration was obtained by measuring silver behenate.57 The program pyFAI 58 was View Article Online DOI: 10.1039/C9NJ00469F 4 5 used to integrate the 2D SAXS data into 1D data. 6 7 The data were then subtracted by the background using PRIMUS software.59 The 8 9 maximum particle dimension Dmax and the pair-distance distribution function P(r) were New Journal of Chemistry Accepted Manuscript 10 11 determined with GNOM.60 The low-resolution structure of the aggregates was 12 13 reconstructed ab initio from the initial portions of the scattering patterns using the Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 program DAMMIN.39 15 16 17 1·10-4 M and 1·10-5M solutions of complexes 1-3 were prepared in different 18 water/DMSO mixtures (0, 25, 50, 75, 90% water contents) and also for gold complex: 19 20 pyrene solutions (1:1) at 1·10-5M concentration of host. 21 22 23 Spectroscopic absorption and emission titrations 24 25 A 0.1mL aliquot of a 1·10-3 M solution of pyrene in CH2Cl2 was added to a 10 mL 26 27 volumetric flask. The solvent was evaporated and MilliQ water was added to the mark. 28 The flask was sonicated for 10 min before use. HCl 0.1M and NaOH 0.1M were used to 29 30 adjust the pH values to 7, which were measured on a MeterLab 240 pH meter. 31 32 Absorption titrations. 3 ml of a neutral 1·10-5M aqueous solutions of pyrene were 33 34 introduced in a 1 cm path absorption cuvette. Different amounts of neutral aqueous 35 36 gold(I) complex (1-3) solutions were introduced both in the sample cuvette and at the 37 38 blank cuvette in order to perform differential absorption spectroscopy and record the 39 resulting spectra of the pyrene:gold adduct. 40 41 42 Emission titrations. 3 ml of a 1·10-5M aqueous solutions of pyrene were introduced in 43 a 1 cm path emission cuvette. Different amounts of neutral aqueous gold(I) complex (1- 44 45 3) solutions were introduced in the cuvette and the corresponding emission spectra were 46 47 recorded in each point. The resulting variations recorded for the emission were plot 48 49 against number of equivalents of gold complex added. The resulting data was fitted 50 following the equation derived by Lehn61 in order to retrieve the association constants 51 52 values. 53 54 55 Theoretical Calculations. 56 57 Calculations were carried out using the Gaussian09 package.62 The hybrid density 58 59 function method known as B3LYP was applied.63,64 All electron basis sets having 60 22 Page 23 of 30 New Journal of Chemistry 1 2 3 valence triple- quality adding a polarization function in all atoms were DOI: used. 65,66 View Article Online 10.1039/C9NJ00469F 4 5 Geometry optimizations were carried out on the full potential-energy surface without 6 7 symmetry restrictions and confirmed as mínima by vibrational analysis. 8 9 Preparation of cholate hydrogels New Journal of Chemistry Accepted Manuscript 10 11 12 The preparation of these hydrogels has been performed following the procedure 13 reported in the literature.52,67 In case of doped hydrogels containing gold complexes and Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 pyrene, the gelation has been carried out adding 50 L of the 1·10-4M solutions of 1-3 16 17 on a 1.5 mL of 30 mM solution of Zn(NO3)2· 6H2O. Then, 1.5 mL of a solution of 18 19 sodium cholate (60 mM) is added at room temperature. The sonication (ultrasonic bath) 20 during 25-30 seconds facilitates the gel formation. 21 22 23 A solution of pyrene (9 L, 5.5·10-4M) was also added in the formation of the cholate 24 25 hydrogels containing this chromophore. 26 27 28 29 Synthesis and Characterization 30 31 32 Synthesis of AuCl(TPPTS). 33 34 This complex was synthesized following a slight modification of the previously 35 36 reported procedure.9 A solution of triphenylphosfine-3,3’,3’’-trisulfonic acid trisodium 37 38 salt, TPPTS, (0.1500 g, 0.264mmol) in methanol (15 mL) was added to a solution of 39 [AuCl(tht)] (0.1029g, 0.264 mmol) in dichloromethane (15 mL). After 24 hour of 40 41 stirring the solution was concentrated to ca. 15 mL and diethyl ether (20 mL) was added 42 43 in order to initiate the precipitation of a white product. The solid was separated by 44 45 filtration, recrystallized with dichloromethane /diethyl ether and dried under vacuum. 46 Yield: 45% (0.0691 g). IR (KBr, cm-1): 3055 (Csp2-H), 1465 (C=C), 1280 and 1034 47 48 (S=O).1H NMR (D2O, 400 MHz): δ 8.15-8.00 (m,6H, P-C-CH-C-S + S-CH-CH), 7.85- 49 50 7.65 (m, 6H, CH-CH-CH + P-C-CH-CH) ppm. 31P NMR (D2O, 162.0 Hz):  34.1 ppm. 51 52 Synthesis of N[Au(C≡C-CH2)PTA]3 (1) 53 54 55 This compound was prepared following a slightly modified previously described 56 methodology.36 KOH (0.038g, 0.67 mmol) was added to a solution of tripropargylamine 57 58 (30 L, 0.21 mmol) in methanol (15 mL). After 30 min stirring, was added a solution of 59 60 23 New Journal of Chemistry Page 24 of 30 1 2 3 [AuClPTA] (0.252g, 0.646 mmol) in dichloromethane (25 mL). After 96 DOI: hours of View Article Online 10.1039/C9NJ00469F 4 5 stirring the solution was filtered through Celite, concentrated to ca. 20 mL and hexane 6 7 (20 mL) was added in order to initiate the precipitation of an orange solid. The product 8 was isolated by filtration, and then recrystallized with dichloromethane/ hexane and 9 New Journal of Chemistry Accepted Manuscript 10 dried under vacuum. Yield: 52% (0.133g). IR (KBr, cm-1): 1240 (C-N), 2000 (C≡C), 11 12 728 (C-P). 1H NMR (CDCl3:, 400 MHz): δ 4.57 (d, J=12.8 Hz, 9H, N-CH2-N), 4.49 (d, 13 31P J=12.8 Hz, 9H, N-CH2-N), 4.30 (s, 18H, N-CH2-P), 3.5 (s, 6H, C-CH2-N) ppm. Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 NMR (CDCl3, 161.9 MHz):  -40.1 ppm. ESI-MS(+): m/z 1191.1977 ([M + H]+; calcd 16 17 m/z 1191.1903). Anal. Calcd (%) for C27H42Au3N10P3: C 27.24, H 3.56, N 11.77. 18 19 Found: C 27.57, H 3.30, N 12.00. 20 21 Synthesis of N[Au(C≡C-CH2)DAPTA]3 (2) 22 23 24 This compound was prepared following a slightly modified previously described 25 methodology.38 The same procedure than in the synthesis of 1 was used but stirring the 26 27 reaction mixture for 72 h instead of 96 h and using AuCl(DAPTA) (0.243 mg, 0.528 28 29 mmol) instead of AuCl(PTA) and 26 µL ( 0.183 mmol) of tripropargylamine and 0.038 30 31 g (0.67 mmol) of KOH. Yield: 35% (0.087 g). IR (KBr, cm-1): 2098 (CC), 1630 32 33 (C=O), 1427 (CH2-P), 1234 (C-N). 1H NMR (CDCl3, 400 MHz):  5.82-5.63 (m, 6H, 34 N-CH2-N + N-CH2-P), 4.85-4.95 (m, 3H, N-CH2-N), 4.70-4.65 (m, 6H, N-CH2-P + N- 35 36 CH2-N), 4.10-4.06 (m, 6H, N-CH2-P + N-CH2-N), 3.85 (s, 6H, N-CH2-P), 3.55 (s, 3H, 37 38 N-CH2-P), 3.50 (s, 6H, C-CH2-N), 2.11 (s, 18H, CO-CH3) ppm. 31P NMR (D2O, 161.9 39 40 MHz):  -13.9 ppm. ESI-MS(+): m/z 1407.2604 ([M + H]+; calcd m/z 1407.2603). 41 Anal. Calcd (%) for C36H54Au3N10O6P3: C 30.74, H 3.87, N 9.96. Found: C 30.65, H 42 43 3.82, N 10.12. 44 45 46 47 Synthesis of N[Au(C≡C-CH2)TPPTS]3 (3) 48 49 50 The synthesis of this compound was performed following the same experimental 51 procedure than in 2 but using only methanol as solvent and diethyl ether as precipitating 52 53 agent instead of hexane and AuCl(TPTTS) (0.250 mg, 0.312 mmol) instead of 54 55 AuCl(PTA) and 15 µL (0.106 mmol) of tripropargylamine and 0.018 g (0.315 mmol) of 56 KOH.Yield: 16% (0.040 g). White solid. IR (KBr, cm-1): 3055 (Csp2 – H), 2100 (CC), 57 58 1465 (C=C (Ar)), 1034 (S=O). 1H NMR (D2O, 400MHz):  8.06-7.35 (m, 36H, Pho + 59 60 24 Page 25 of 30 New Journal of Chemistry 1 2 3 DOI: Phm + Php), 3.60-3.50 (s, 6H, N-CH2-CC) ppm. 31P NMR (D2O, 161.9 MHz): 42.5 View Article Online 10.1039/C9NJ00469F 4 5 ppm. ESI-MS(-): m/z 773.2966 ([M- 7Na++4H++3H2O]3-; calcd m/z 773.2988). Anal. 6 7 Calcd (%) for C63H42Au3NNa9O27P3S9: C, 31.21; H, 1.75; N, 0.58; S, 11.90. Found: C, 8 9 30.97; H, 1.74; N, 0.62; S, 12.03. New Journal of Chemistry Accepted Manuscript 10 11 12 13 Acknowledgements Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 16 The authors are grateful to the Ministry of Economy, Industry and Competitiveness of 17 18 Spain (AEI/FEDER, UE Project CTQ2016-76120-P). This work was also supported by 19 the Associated Laboratory for Sustainable Chemistry, Clean Processes and 20 21 Technologies, LAQV, which is financed by national funds from FCT/MEC 22 23 (UID/QUI/50006/2013) and co-financed by the ERDF under the PT2020 Partnership 24 25 Agreement (POCI-01-0145-FEDER-007265). This research was supported by a Marie 26 Curie Intra European Fellowship within the 7th European Community Framework 27 28 Programme (R.G.). A.M. thanks FCT for a post-doctoral grant 29 30 (SFRH/BPD/69210/2010). SAXS experiments were performed at the NCD-SWEET 31 32 beamline of the ALBA Synchrotron Light Facility in collaboration with the ALBA staff. 33 Allocation of computer facilities at IQTCUB is also acknowledged, supported by María 34 35 de Maeztu program (MDM-2017-0767). 36 37 38 39 40 Supporting Information 41 42 1H 31P{1H} and NMR characterization data of 1-3. 1H NMR spectra at different 43 44 concentrations; SAXS data of 1-3 at different concentrations and temperatures; Optical 45 46 microscoy images of 1-3 at 1·10-4M; absorption and emission titrations of pyrene in the 47 48 presence of 1-3. Optical and electronic microscopy images of hybrid cholate aggregates. 49 50 51 52 53 54 55 56 57 58 59 60 25 New Journal of Chemistry Page 26 of 30 1 2 3 4 References View Article Online DOI: 10.1039/C9NJ00469F 5 1 B. H. Northrop, Y.-R. Zheng, K.-W. Chi and P. J. Stang, Acc. Chem. Res., 2009, 42, 6 7 8 1554. 9 2 L. A. Estroff and A. D. Hamilton, Chem. Rev., 2004, 104, 1201; New Journal of Chemistry Accepted Manuscript 10 11 3 A. Pinto, N. Svahn, J.C. Lima and L. Rodríguez, Dalton Trans. 2017, 46, 11125. 12 4 a) R. E. Bachman, A. J. Zucchero and J. L. Robinson, Langmuir, 2012, 28, 27; (b) P. 13 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 Terech, G. Gebel and R. Ramasseul, Langmuir, 1996, 12, 4321; (c) B. Xing, M. F. 16 Choi, Z. Zhou and B. Xu, Langmuir, 2002, 18, 9654. 17 18 5 J.C. Lima and L. Rodríguez, Inorganics 2015, 3, 1. 19 6 P. Howlader and P. S. Mukherjee, Chem. Sci., 2016, 7, 5893. 20 21 7 Y.-X. Ye, W.-L. Liu and B.-H. Ye, Catal. Commun. 2017, 89, 100. 22 23 8 M. Araújo and B. Escuder, ChemistrySelect 2017, 2, 854. 24 9 S. Sanz, L.A. Jones, F. Mohr, M. Laguna. Organometallics 2007, 26, 952. 25 26 10 27 P. Sutar and T. K. Maji, Chem.Commun., 2016, 52, 8055. 28 11 L. Giestas, R. Gavara, E. Aguiló, N. Svahn, J.C. Lima and L. Rodríguez, Supramol. 29 30 Chem., 2018, 30, 278. 31 12 E. Aguiló, A.J. Moro, R. Gavara, I. Alfonso, Y. Pérez, F. Zaccaria, C. Fonseca 32 33 34 Guerra, M. Malfois, C. Baucells, M. Ferrer, J.C. Lima and L. Rodríguez, Inorg. Chem. 35 2018, 57, 1017. 36 37 13 A. Kishimura, T. Yamashita and T. Aida, J. Am. Chem. Soc., 2005, 127, 179. 38 14 B. D. Yuhas, A. L. Smeigh, A. P. S. Samuel, Y. Shim, S. Bag, A. P. Douvalis, M. R. 39 40 Wasielewski and M. G. Kanatzidis, J. Am. Chem. Soc., 2011, 133, 7252. 41 42 15 X. He, Y. Xue, C.-C. Li, Y. Wang, H. Jiang and L. Zhao, Chem. Sci., 2018, 9, 1481. 43 16 L. Fü, Y. Fang and G.J. Blanchard Spectrochim Acta A Mol Biomol. Spectrosc 2009, 44 45 46 74, 991. 47 17 R. Ferrer, J.L. Beltrán and J. Guiteras, Talanta 1998, 45, 1073. 48 49 18 N. P.E. Barry, O. Zava, W. Wu, J. Zhao and B. Therrien, Inorg. Chem. Commun. 50 51 2012, 18, 25. 52 19 53 A. M. Lifschitz, M. S. Rosen, C. M. McGuirk and C. A. Mirkin, J. Am. Chem. Soc., 54 2015, 137, 7252. 55 56 20 B. Kemper, Y.R. Hristova, S. Tacke, L. Stegemann, L.S. van Bezouwen, M.C.A. 57 58 Stuart, J. Klingauf, C.A. Strassert and P. Besenius, Chem. Commun. 2015, 51, 5253. 59 60 26 Page 27 of 30 New Journal of Chemistry 1 2 3 21 E. Lee, H. Ju, Y. Kang, S. S. Lee, K.-M. Park, Chem. Eur. J. 2015, 21, 6052.DOI: 10.1039/C9NJ00469F View Article Online 4 5 22 O. Abdel-Aziz, A. M. El Kosasy and S. M. El-Sayed Okeil, J Fluoresc 2014, 24, 6 7 549. 8 23 V.N.S. Occello and A.V. Veglia, Anal. Chim. Acta 2011, 689, 97. 9 New Journal of Chemistry Accepted Manuscript 10 24 M. Kfoury, D. Landy and S. Fourmentin, Molecules 2018, 23, 1204. 11 25 R. R. Kashapov, S.V. Kharlamov, E.D. Sultanova, R.K. Mukhitova, Y.R. 12 13 Kudryashova, L.Y. Zakharova, A.Y. Ziganshina and A.I. Konovalov, Chem. Eur. J. Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 2014, 20, 14018. 16 17 26 R. Gramage-Doria, D. Armspach, D. Matt, Coord. Chem. Rev. 2013, 257, 776. 18 27 L. Rodríguez, J.C. Lima, M. Ferrer, O. Rossell, M. Engeser, Inorg. Chim. Acta 2012, 19 20 21 381, 195. 22 28 V. Mishra, A. Raghuvanshi, A. Kumar Saini and S. M. Mobin, J. Organomet. Chem. 23 24 2016, 813, 103. 25 29 26 N. Svahn, A.J. Moro, C. Roma-Rodrigues, R. Puttreddy, K.Rissanen, P.V. Baptista, 27 A. R. Fernandes, J.C. Lima and L. Rodríguez, Chem.-Eur. J. 2018, 24, 14654. 28 29 30 X. He, E. C.-C. Cheng, N. Zhu, V. W.-W. Yam, Chem. Commun., 2009, 4016. 30 31 Y.-P. Zhou, E.-B. Liu, J. Wang, H.-. Chao, Inorg. Chem. 2013, 52, 8629. 31 32 32 33 J.F. Fernández-Sánchez, A. Segura Carretero, C. Cruces-Blanco and A. Fernández- 34 Gutiérrez, Anal. Chim. Acta 2011, 506, 1. 35 36 33 D. Patra and A.K. Mishra, Talanta 2001, 55, 143. 37 34 G. Bains, A. B. Patel and V. Narayanaswami, Molecules 2011, 16, 7909. 38 39 35 S. V. Aathimanikandan, E. N. Savariar and S. Thayumanavan, J. Am. Chem. Soc. 40 41 2005, 127, 14922. 42 36 R. Laishram and U. Maitra, Chem. Asian J. 2017, 12, 1267. 43 44 37 45 A. Chakrabarty, U. Maitra and A. D. Das, J. Mater. Chem. 2012, 22, 18268. 46 38 E. Vergara, E. Cerrada, A. Casini, O. Zava, Mariano Laguna and P. J. Dyson, 47 48 Organometallics 2010, 29, 2596. 49 39 (a) D. I. Svergun, Restoring Low Resolution Structure of Biological Macromolecules 50 51 52 from Solution Scattering Using Simulated Annealing. Biophys J., 1999, 2879. (b) A. 53 Krebs, H. Durchschlag and P. Zipper, Small Angle X-Ray Scattering Studies and 54 55 Modeling of Eudistylia vancouverii Chlorocruorin and Macrobdella decora 56 57 Hemoglobin. Biophys J., 2004, 2, 1173. 58 40 T. I. Mizan, P. E. Savage and R. M. Ziff, J. Phys. Chem. 1996, 100, 403. 59 60 27 New Journal of Chemistry Page 28 of 30 1 2 3 41 R. Gavara, E. Aguiló, C. Fonseca Guerra, L. Rodríguez and J.C. Lima, Inorg. Chem. View Article Online DOI: 10.1039/C9NJ00469F 4 5 2015, 54, 5195. 6 42 S. Pandey, M. Ali, A. Bishnoi, A. Azam, S. Pandey and H.M. Chawla, J. Fluoresc. 7 8 2008, 18, 533. 9 New Journal of Chemistry Accepted Manuscript 10 43 D. Kim, R. Amos, M. Gauthier and J. Duhamel, Langmuir 2018, 34, 8611. 11 44 A. Yekta, J. Duhamel, P. Brochard, H. Adiwidjaja and M.A. Winnik, 12 13 Macromolecules 1993, 26, 1829. Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 45 E. R. T. Tiekink and J. Zukerman-Schpector, Cryst. Eng. Comm, 2009, 11, 1176. 16 17 46 D. Nolan, B. Gil, L. Wang, J. Zhao and S.M. Draper, Chem. Eur. J. 2013, 19, 15615. 18 47 L. Rodríguez, J.C. Lima, M. Ferrer, O. Rossell and M. Engeser, Inorg. Chim. Acta 19 20 21 2012, 381, 195. 22 48 V. Ramamurthy, S. Jockusch and M. Porel, Langmuir 2015, 31, 5554. 23 24 49 D. C. Dong and M. A. Winnik Can. J. Chem. 1984, 62, 2560. 25 50 26 J.R. Lakowicz, Solvent effects on emission spectra. In Principles of Fluorescence 27 Spectroscopy, 2nd ed.; Lakowicz, J.R., Ed.; Kluwer Academic/ Plenum Publisher: New 28 29 York, NY, USA, 1999; pp. 185-189. 30 51 A. Nakajima, J. Mol. Spectrosc. 1976, 61, 467. 31 32 52 33 A. Chakrabarty, U. Maitra and A.D. Das, J. Mater. Chem. 2012, 22, 18268. 34 53 Molecular Gels, Materials with Self-Assembled Fibrillar Networks, ed. R. G. Weiss 35 36 and P. Terech, Springer, 2006, pp. 751–752. 37 54 E. Aguiló, R. Gavara, J.C. Lima, J. Llorca and L. Rodríguez, J. Mater. Chem. C 2013, 38 39 1, 5538. 40 41 55 K.A. Connors, Binding Constants: The Measurement of Molecular Complex 42 43 Stability, John Wiley & Sons, New York, 1987. 44 56 45 E. Vegara, S. Miranda, F. Moh, E. Cerrada, E.R.T. Tiekink, P. Romero, A. Mendía 46 and M. Laguna. Eur. J. Inorg. Chem., 2007, 2926. 47 48 57 T. C. Huang, H. Toraya, T. N. Blanton and Y. Wu, J. Appl. Cryst., 1993, 26, 180. 49 58 J. Kieffer and D. Karkoulis, J. Phys.: Conf. Ser., 2013, 425, 202012. 50 51 59 52 J. App, V. Konarev, V. V. Volkov, A. V. Sokolova, M. H. J. Koch and D. I. Svergun, 53 J. Appl. Cryst., 2003, 36, 1277. 54 55 60 D. I. Svergun, J. Appl Cryst., 1992, 25, 495. 56 61 P. Cjudić, M. Zjinić, V. Tomisjić, V. Simeon, J.-P. Vigneron and J.-M. Lehn, J. 57 58 Chem. Soc., Chem. Commun. 1995, 1073. 59 60 28 Page 29 of 30 New Journal of Chemistry 1 2 3 62 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. View Article Online DOI: 10.1039/C9NJ00469F 4 5 Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. 6 7 Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, 8 M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. 9 New Journal of Chemistry Accepted Manuscript 10 Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, 11 12 M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. 13 Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 14 15 Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. 16 17 Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. 18 19 Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. 20 21 Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O. 22 Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09 (Revission 23 24 B.1), Gaussian Inc., Wallingford CT, 2010. 25 63 26 A. D. Becke, J. Chem. Phys. 1993, 98, 5648. 27 64 C. Lee, W. Yang R. G. Parr, Phys. Rev. B 1988, 37, 785. 28 29 65 A. Schaefer, C. Huber, R. Ahlrichs, J. Chem. Phys. 1994, 100, 5829. 30 66 D. Andrae, U. Haeussermann, M. Dolg, H. Stoll, H. Preuss, Theor. Chim. Acta 1990, 31 32 33 77, 123 34 67 R. Gavara, J. Mateos, F. Sabaté, R. Belda, J. M. Llinares, E. García-España and L. 35 36 Rodríguez, Eur. J. Inorg. Chem. 2018, 4550. 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 29 New Journal of Chemistry Page 30 of 30 View Article Online DOI: 10.1039/C9NJ00469F 1 2 3 4 5 6 7 8 New Journal of Chemistry Accepted Manuscript 9 Published on 02 May 2019. Downloaded by Universitat Autonoma de Barcelona on 5/2/2019 7:53:55 AM. 10 11 12 13 14 15 16 17 18 19 20 21 22 23 139x62mm (96 x 96 DPI) 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60