Formation Of Supramolecular Assemblies Research Articles

Host‐Guest Assemblies of Polyoxovanadate Clusters as Supramolecular Catalysts

Supramolecular functional materials can be used to overcome some of the most challenging tasks in materials science, where the dynamic nature of supramolecular interactions can be leveraged to fine‐tune the properties of the material. The Lindqvist hexavanadate family of polyoxometalates are interesting candidates for supramolecular materials due to their redox and Lewis acid properties that enable their application in energy conversion or catalysis. Despite their promising potential, hexavanadate clusters are underrepresented in supramolecular materials, mainly due to the synthetic challenges related to their inherent reactivity. In this work, pillar[5]arene was successfully grafted onto a Lindqvist hexavanadate and the resulting structure was confirmed by single crystal X‐ray diffraction, presenting the first example of a crystal structure of a polyoxometalate covalently functionalized with a pillar[5]arene. By introducing a ditopic guest molecule that could interlink pillar[5]arene moieties, host‐guest interactions were leveraged as the driving force for the formation of supramolecular assemblies incorporating hexavanadate clusters in a controlled manner. The enhanced catalytic performance of the resulting aggregates confirmed their potential application as functional catalytic materials. This novel approach for developing hexavanadate‐based catalysts reported here showcases the potential of using host‐guest interactions as a means to introduce catalytically active metal‐oxo clusters into supramolecular frameworks.

Host-Guest Assemblies of Polyoxovanadate Clusters as Supramolecular Catalysts.

Supramolecular functional materials can be used to overcome some of the most challenging tasks in materials science, where the dynamic nature of supramolecular interactions can be leveraged to fine-tune the properties of the material. The Lindqvist hexavanadate family of polyoxometalates are interesting candidates for supramolecular materials due to their redox and Lewis acid properties that enable their application inenergy conversion or catalysis. Despite their promising potential, hexavanadate clusters are underrepresented in supramolecular materials, mainly due to the synthetic challenges related to their inherent reactivity. In this work, pillar[5]arene was successfully grafted onto a Lindqvist hexavanadate and the resulting structure was confirmed by single crystal X-ray diffraction, presenting the first example of a crystal structure of a polyoxometalate covalently functionalized with a pillar[5]arene. By introducing a ditopic guest molecule that could interlink pillar[5]arene moieties, host-guest interactions were leveraged as the driving force for the formation of supramolecular assemblies incorporating hexavanadate clusters in a controlled manner. The enhanced catalytic performance of the resulting aggregates confirmed their potential application as functional catalytic materials. This novel approach for developing hexavanadate-based catalysts reported here showcases the potential of using host-guest interactions as a means to introduce catalytically active metal-oxo clusters into supramolecular frameworks.

Supramolecular Co (II) Complex Fabricated From Adenine Derivative: Synthesis, Crystal Structure, Hirshfeld Surface, DFT Optimization, Anticancer, and Molecular Docking Studies

ABSTRACTThis article presents the synthesis of a novel mononuclear Co (II) complex [Co(9‐BuA)2Cl2] (1), its characterization, supramolecular packing pattern, theoretical calculations, anticancer properties, and molecular docking studies. Complex 1 was generated from 9‐butyl adenine (9‐BuA) building block and characterized by spectroscopic methods (FT‐IR, mass, elemental analysis) and single crystal X‐ray diffraction analysis. The cobalt (II) ion in complex 1 is distorted in its tetrahedral environment. The Co+2 is coordinated to the two rare N1 binding sites of the pyrimidinate moiety of two 9‐BuA ligands and two chlorine atoms occupying the axial positions. Both intramolecular and intermolecular hydrogen bonds support the formation of supramolecular assembly and stabilize the crystal structure. The nature of the intermolecular interactions in the supramolecular network was also decoded by Hirshfeld surface analysis and molecular surface contours (dnorm). The percentage contributions are represented by 2D fingerprint plots. The average energy between dimers was determined by the energy framework analysis, and the crystal packing's three‐dimensional topology was also investigated. Density functional theory (DFT) has been used to ascertain the geometry and interactions in the complex. The cytotoxic effects of Co (II) complex 1 and corresponding 9‐BuA ligand were investigated in Dalton's lymphoma (DL) malignant cancer cells and on normal peripheral blood mononuclear cells (PBMCs) to evaluate their anticancer activity. Finally, molecular docking analyses have been carried out to analyze the nature of molecular interactions between Co (II) complex 1 and the receptor.

Molecular modeling to elucidate the dynamic interaction process and aggregation mechanism between natural organic matters and nanoplastics

The interactions of nanoplastics (NPs) with natural organic materials (NOMs) dominate the environmental fate of both substances and the organic carbon cycle. Their binding and aggregation mechanisms at the molecular level remain elusive due to the high structural complexity of NOMs and aged NPs. Molecular modeling was used to understand the detailed dynamic interaction mechanism between NOMs and NPs. Advanced humic acid models were used, and three types of NPs, i.e., polyethylene (PE), polyvinyl chloride (PVC), and polystyrene (PS), were investigated. Molecular dynamics (MD) simulations revealed the geometrical change of the spontaneous formation of NOMs-NPs supramolecular assemblies. The results showed that pristine NPs initially tend to aggregate homogeneously due to their hydrophobic nature, and then NOM fragments are bound to the formed NP aggregates mainly by vdW interaction. Homo- and hetero-aggregation between NOMs and aged NPs occur simultaneously through various mechanisms, including intermolecular forces and Ca2+ bridging effect, eventually resulting in a mixture of supramolecular structures. Density functional theory calculations were employed to characterize the surface properties and reactivity of the NP monomers. The molecular polarity indices for unaged PE, PS, and PVC were 3.1, 8.5, and 22.2 ​kcal/mol, respectively, which increased to 43.2, 51.6, and 42.2 ​kcal/mol for aged NPs, respectively, indicating the increase in polarity after aging. The vdW and electrostatic potentials of NP monomers were visualized. These results clarified the fundamental aggregation processes, and mechanisms between NPs and NOMs, providing a complete molecular picture of the interactions of nanoparticles in the natural aquatic environment.

TPE-embedded butterfly bis-crown ether with controllable conformation and supramolecular chiroptical property

Understanding how subtle structural differences between macrocyclic conformational isomers impact their properties and separation has garnered increasing attention in the field of supramolecular synthetic chemistry. In this work, a series of tetraphenylene (TPE)-embedded butterfly bis-crown ether macrocycles (BCE[n], n = 4–7), comprising two crown ether side rings and a TPE core, are synthesized through intramolecular McMurry coupling. Unexpectedly, the presence of flexible oligoethylene chains with varying lengths are found to influence molecular conformation via multiple intramolecular interactions, resulting in the formation of two stabilized conformers with specific semi-rigid symmetric/asymmetric structures (sym-BCE[n] and asym-BCE[n], n = 5, 6). Moreover, it is noteworthy that neither symmetric nor asymmetric conformers are present in the more rigid BCE[4] or the more flexible BCE[7]. Interestingly, these conformers display distinct fluorescence properties and host-guest binding abilities, and only sym-BCE[5] can serve as a host for chiral polymer binding, resulting in the formation of chiral supramolecular assemblies through host-guest interaction induced chirality. Moreover, both circular dichroism and circularly polarized luminescence signals of the obtained assemblies can be switched off by the addition of sodium ion, suggesting potential applications in the field of dynamic chiral materials.

Hydrogen bonding, halogen bonding and C–H…π interactions governing the supramolecular architecture of 1-(4-(4-bromophenyl)piperazin-1-yl)-2-chloroethan-1-one: Insights from X-ray crystallography, DFT calculations and urease inhibitory assessment

The use of organic ligands for the generation of supramolecular architectures exhibiting interesting structural properties in crystal engineering have garnered significant attention. In this context, the current work highlights the use of 1-(4-(4-bromophenyl)piperazin-1-yl)-2-chloroethan-1-one (3) as a valuable synthon for evaluating the conspicuous role of several types of noncovalent interactions governing the formation of supramolecular assemblies. Compound 3 was successfully synthesized in good yield using a facile two-step approach and characterized through spectroscopic and X-ray crystallographic methods. Noncovalent interactions including C—H…O, C—H…Cl, C—H…π as well as C—Br…Cl halogen bonds were found as the key contacts in the crystal packing of compound 3. DFT calculations were employed to identify and assess the impact of the C—Br…Cl halogen bond, utilizing MEP, QTAIM, and NBO analyses. These studies confirmed that the Br atom acts as the halogen bond donor and the Cl atom as the halogen bond acceptor. Assessment of urease inhibitory efficacy revealed that the tested compound exhibits a 16-folds superior inhibition than thiourea. Computational modeling analysis augmented the in vitro results by exhibiting numerous favorable binding interactions between compound 3 and active site residues such as TYR32, LYS709, PHE712, ASP730, VAL744 and MET746. The pharmacokinetic evaluation classified the investigated piperazine derivative into a druggable compound.

Homochiral and Heterochiral Self-Sorting Assemblies of Antiaromatic Ni(II) Norcorrole Dimers.

Recently, π-π stacked antiaromatic π-systems have received considerable attention because they can exhibit stacked-ring aromaticity due to substantial intermolecular orbital interactions. Here, we report three antiaromatic norcorrole dimers that self-assemble to form supramolecular architectures through chiral self-sorting. A 2,2'-linked norcorrole dimer with 3,5-di-tert-butylphenyl groups forms a π-stacked dimer both in solid and solution states via homochiral self-sorting. Its association constant in solution is (3.6±1.7)×105 M-1 at 20 °C. In the solid state, 3,3'-linked norcorrole dimers with 3,5-di-tert-butylphenyl and phenyl groups afford macrocyclic and helical supramolecular assemblies via heterochiral and homochiral self-sorting, respectively. Notably, the subtle modification in the substituent resulted in a complete change in the structure of the aggregates and the chiral self-sorting mode. The present findings demonstrate that structural manipulation in antiaromatic monomer units leads to the formation of various supramolecular assemblies on the basis of the attractive interactions between antiaromatic π-systems.

Unraveling the influence of aromatic endcaps in peptide self-assembly

Aromatic peptides are an emerging class of building units for molecular self-assembly and creation of functional biomaterials. The strength of aromatic association plays an essential role in the self-assembly of aromatic peptides. Here, we design a series of aromatic peptides with different hydrophobic domains but the same peptide sequence. The hydrophobicity and aromaticity can be carefully regulated by the number of benzene rings and the alkyl spacer between the benzene and peptide regions. Upon the continuous enhancement of aromaticity, diverse supramolecular nanostructures, including nanotubes, nanofibers, and short helical ribbons, were clearly observed. The peptide with diphenyl groups exhibits the highest regularity of molecular packing, due to the synergy of force balance between hydrogen bonding and π–π interactions. In addition, the incorporation of a spacer in between the aromatic and peptide regions facilitates the self-assembly capability, as the interference between aromatic association and hydrogen bonding is hindered. These dramatic results demonstrate that aromaticity serves as an effective and robust parameter in the molecular arrangement, providing a new perspective into the formation and evolution of supramolecular assembly.

Self-Adaptive Aromatic Cation-π Driven Dimensional Polymorphism in Supramolecular Polymers for the Photocatalytic Oxidation and Separation of Aromatic/Cyclic Aliphatic Compounds.

The phenomenon of polymorphism is ubiquitous in nature, the controlled manipulation of which not only increases our ontological understanding of nature but also facilitates the conceptualization and realization of novel functional materials. However, achieving targeted polymorphism in supramolecular assemblies (SAs) remains a formidable challenge, largely because of the constraints inherent in controlling the specific binding motifs of noncovalent interactions. Herein, we propose self-adaptive aromatic cation-π binding motifs to construct polymorphic SAs in both the solid and solution states. Using distinct discrete cation-π-cation and long-range cation-π binding motifs enables control of the self-assembly directionality of a C2h-symmetric bifunctional monomer, resulting in the successful formation of both two-dimensional and three-dimensional crystalline SAs (2D-CSA and 3D-CSA). The differences in the molecular packing of 3D-CSA compared with that of 2D-CSA significantly improve the charge separation and carrier mobility, leading to enhanced photocatalytic activity for the aerobic oxidation of thioanisole to methyl phenyl sulfoxide (yield of 99 % vs 57 %). 2D-CSA, which has a vertical extended structure with favorable stronger interaction with toluene though face-to-face cation-π interactions than methylcyclohexane, shows higher toluene/methylcyclohexane separation efficiency than 3D-CSA (96.9 % for 2D-CSA vs 56.3 % for 3D-CSA).

Self-Assembly of a Novel Pentapeptide into Hydrogelated Dendritic Architecture: Synthesis, Properties, Molecular Docking and Prospective Applications.

Currently, ultrashort oligopeptides consisting of fewer than eight amino acids represent a cutting-edge frontier in materials science, particularly in the realm of hydrogel formation. By employing solid-phase synthesis with the Fmoc/tBu approach, a novel pentapeptide, FEYNF-NH2, was designed, inspired by a previously studied sequence chosen from hen egg-white lysozyme (FESNF-NH2). Qualitative peptide analysis was based on reverse-phase high performance liquid chromatography (RP-HPLC), while further purification was accomplished using solid-phase extraction (SPE). Exact molecular ion confirmation was achieved by matrix-assisted laser desorption-ionization mass spectrometry (MALDI-ToF MS) using two different matrices (HCCA and DHB). Additionally, the molecular ion of interest was subjected to tandem mass spectrometry (MS/MS) employing collision-induced dissociation (CID) to confirm the synthesized peptide structure. A combination of research techniques, including Fourier-transform infrared spectroscopy (FTIR), fluorescence analysis, transmission electron microscopy, polarized light microscopy, and Congo red staining assay, were carefully employed to glean valuable insights into the self-assembly phenomena and gelation process of the modified FEYNF-NH2 peptide. Furthermore, molecular docking simulations were conducted to deepen our understanding of the mechanisms underlying the pentapeptide's supramolecular assembly formation and intermolecular interactions. Our study provides potential insights into amyloid research and proposes a novel peptide for advancements in materials science. In this regard, in silico studies were performed to explore the FEYNF peptide's ability to form polyplexes.

Supramolecular Self-Assembly of Proteins Promoted by Hybrid Polyoxometalates.

Controlling the formation of supramolecular protein assemblies and endowing them with new properties that can lead to novel functional materials is an important but challenging task. In this work, a new hybrid polyoxometalate is designed to induce controlled intermolecular bridging between biotin-binding proteins. Such bridging interactions lead to the formation of supramolecular protein assemblies incorporating metal-oxo clusters that go from several nanometers in diameter up to the micron range. Insights into the self-assembly process and the nature of the resulting biohybrid materials are obtained by a combination of Small Angle X-ray Scattering (SAXS), Transmission Electron Microscopy (TEM), and Dynamic Light Scattering (DLS), along with fluorescence, UV-vis, and Circular Dichroism (CD) spectroscopy. The formation of hybrid supramolecular assemblies is determined to be driven by biotin binding to the protein and electrostatic interactions between the anionic metal-oxo cluster and the protein, both of which also influence the stability of the resulting assemblies. As a result, the rate of formation, size, and stability of the supramolecular assemblies can be tuned by controlling the electrostatic interactions between the cluster and the protein (e.g., through varying the ionic strength of the solution), thereby paving the way toward biomaterials with tunable assembly and disassembly properties.

The Design of Supramolecular Assemblies with Metal Salt as Precursors Enables The Growth of Stable Polymeric Carbon Nitride Photoanodes

AbstractPolymeric carbon nitrides (CN) have gained significant interest as photoanodes in photoelectrochemical cells (PEC). A widely researched approach for synthesizing CN films with controlled optical and photoelectrochemical properties relies on using supramolecular assemblies as the precursors for thermal polymerization over a transparent conductive substrate. However, the formation of supramolecular assemblies is highly dependent on the temperature and solubility in a given solvent, limiting the full potential of this method. Moreover, the intercalation of metal ions is challenging due to the use of polar solvents. Here, this study shows a new way of synthesizing supramolecular assemblies with metal ions using a solvothermal approach. The solvent, monomer composition, salt quantity, reaction temperature, and film thickness are varied in this study. As a result, well‐attached, uniform CN films with good optoelectronic properties are achieved. The synthesized photoactive CN films exhibit very low onset potentials and reach ≈0.13, ≈0.15, and 0.30 ± 0.01 mA cm−2 photocurrents in 0.1 m phosphate buffer (neutral) solution, 0.1 m KOH(aq) (basic) solution, and 0.1 m KOH solution containing 10 vol.% triethanolamine as the hole scavenger, respectively.

Micellar-enhanced ultrafiltration with a novel modified membrane for removal of arsenate and emerging contaminants from water

Toxic metals and Antibiotics appear in water sources have potential threat or adverse effect on health of human being and other living species. The present paper reports a novel micellar-enhanced ultrafiltration process could efficiently remove the toxic metals like arsenate and antibiotics like Levofloxacin and Sulfamethazine from water. Contaminants removal by conventional ultrafiltration membrane is very low. Removal up to 92.8 %, 84.1 % and 95.3 % of Arsenate (AsO43-), Levofloxacin (LF) and Sulfamethazine (SMT) respectively was achieved by micellar-enhanced ultrafiltration with cationic surfactant Benzalkonium chloride as compared to conventional ultrafiltration, which rejected 91.4 %, 8.2 % and 7.9 % of Arsenate, LF, and SMT respectively. Hydrodynamic size of the molecule trapped by micelle enhances significantly helping the separation. The ultrafiltration membrane was modified with copper-chitosan supramolecular assembly and found that molecular weight cut-off decreased because of supramolecular assembly formation. Mechanical properties such as tensile stress and elongation at break were evaluate and it was found that the membrane had significantly higher tensile strength viz. up to 60.9 MPa as compared to virgin Polysulfone membrane 12.7 MPa. Thus, the present work paves the way for future work in the area for removal different contaminants. by micellar-enhanced ultrafiltration.

Supramolecular Assemblies of Melamine-2-Thiobarbiturate and Melamine-Barbiturate-2-Thiobarbiturate: Experimental and Theoretical Studies

In this work, we considered the formation of supramolecular assemblies of melamine-thiobarbiturate and melamine-barbiturate-thiobarbiturate. It is known that thiobarbituric acid can form many tautomers, as well as different motifs due to the change of C2=O to C2=S hydrogen bonds. We formed the crystal. The resulting crystals were studied with scanning electron microscopy (SEM), optical fluorescence microscopy, single crystal and powder (PXRD) X-ray diffraction analyses, and solid state nuclear magnetic resonance (ss NMR). These systems were theoretically studied using density functional theory (DFT) and classical molecular dynamics (MD) simulations. Interestingly, just as in the case of melamine barbiturate, during the crystallization process, hydrogen from the C5 moiety of thiobarbituric acid migrates to the melamine molecule. In addition, the resulting melamine thiobarbiturate crystals exhibit fluorescence behavior in the red region (~565–605 nm), while the melamine barbiturate crystals are fluorescent in the green region (512–542 nm).

Dependence of anti-proliferative activity on chirality and redox potentials (Eh) of new ferrocene derivatives: Synthesis, crystallographic, photophysical and in-silico study

Chiral α-iodoamides (S)-IA-1, (R)-IA-2, (S)-IA-3 and (R)-IA-4 were synthesized and characterized prior to use in the synthesis of four chiral ferrocenyl secondary amines viz. (S)-2-(ferrocenylmethylamino)-N-(1-phenylethyl)acetamide, (S)-FA-5, (R)-2-(ferrocenyl methylamino)-N-(1-phenylethyl)acetamide, (R)-FA-6, (S)-2-(ferrocenylmethylamino)-N-(1-(naphthalen-1-yl)ethyl)acetamide, (S)-FA-7 and (R)-2-(ferrocenylmethylamino)-N-(1-(naphthalen-1-yl)ethyl)acetamide, (R)-FA-8. The purity and composition of the compounds were ascertained by elemental, 1H, 13C NMR, FTIR, UV–visible emission spectral and X-ray diffraction methods. The formation of diverse supramolecular assemblies sustained by several NH…O, CH…O and CH…I intermolecular hydrogen bonding interactions was confirmed by single crystal X-ray diffraction (SCXRD). The impact of Eh and chirality on the anti-proliferative activity of these compounds has been explored. Notably, R-enantiomers are found to be superior to S-enantiomers in the studied MCF 7, IMR 32, HepG2 and L132 cell lines of human origin. In instance, (R)-FA-6 has demonstrated superior activity than cisplatin against MCF 7 (IC 50: 31.38±0.24 μM) and HepG2 (IC 50: 18.78±0.14 μM). Further research, including electrochemical, DFT calculations and a docking analysis, was performed to rationalize and confirm the results.

Multi-anionic polymer templated aggregation induced emission of berberine and its application for protamine sensing

In recent years exploration of aggregation induced emission from the naturally occurring luminogens has garnered significant attention across the globe due to their widespread applications in diverse fields of modern-day research. Herein, we delineate multi-anionic polymer, polystyrene sulfonate (PSS) templated aggregation induced emission (AIE) of a medically important and naturally origin alkaloid, berberine (BBR) and its application towards the quantification of an important bio-analyte, protamine (Pr). Cationic BBR at the vicinity of the polyanionic PSS, partially loses its positive charge which causes the reduction in the electrostatic repulsion between the adjacent dye molecules, promoting their aggregation via π-π staking over the polymer surface. This substantially changes the microenvironment of the dye surrounding, leading to the lowering in its structural swiftness and tendency of intramolecular charge transfer (ICT) state formation. Thus, the dye exhibits amplified emission in the aggregated state. Increase of average lifetime and sluggish nature of anisotropy decay of BBR in the presence of PSS support structural confinement and weakening of non-radiative deexcitation pathways for the dye through the formation of BBR-PSS supramolecular assembly. The formed BBR-PSS assembly displays high sensitivity towards external parameters like ionic strength, temperature but unresponsive to a wide range of pH. Importantly, BBR-PSS has been found to be highly sensitive and selective towards an important polypeptide, Pr. Owing to its high positive charge density, Pr disintegrates the BBR-PSS complex, producing fluorescence turn-off response for the BBR-PSS complex which enables us to quantify Pr in aqueous solution. Notably, this AIE based complex is quite efficient to detect protamine even in 1% human serum matrix as low as ∼ 89 nM in spite of presence of various other interfering bioanalytes.

Extracellular matrix: A regenerative conduit in dentistry

Periodontal disease causes tooth loss by destroying the attachment system and tooth supporting tissues. Periodontal therapy seeks to not only halt the advancement of periodontal disease, but also to repair lost structures caused by disease progression. Extracellular matrix (ECM) is a complex three-dimensional network made up of an array of multidomain macromolecules organised in a cell/tissue-specific manner that serves as a structural scaffold in the formation of supramolecular assemblies in tissue architecture that regulate cell growth and differentiation, thereby providing a suitable biochemical and biomechanical microenvironment for regeneration of lost tissue structures. This article's goal is to provide a simplified and concise understanding of the structure and components of ECM, as well as to shed light on its utility as a regenerative conduit in the field of periodontal regeneration.

Insight into the role of pseudo-halides as multiple hydrogen bond acceptors in the formation of supramolecular 1D assembly of di and trinuclear zinc complexes

In this manuscript we report the synthesis of two new zinc(II) complexes, [(DMSO)2 ZnL1Zn(NCS)2] (1), and [{(N3)ZnL2}2Zn(DMSO)2] (2) that were characterized by elemental and spectral analyses {H2L1 is 2,2-dimethyl-1,3-propanediylbis(iminomethylene)bis(phenol), and H2L2 is 1,2-propanediylbis(iminomethylene)bis(4-chlorophenol)}. The structures have been confirmed by single crystal X-ray diffraction analysis. Both complexes form 1D supramoelcular assemblies where the pseudohalides act as multiple H-bond acceptors (CH•••S,N and NH•••S,N). These assemblies have been analyzed theoretically using DFT calculations, and the energy associated to each contact has been estimated using the quantum theory of atoms-in-molecules. The importance of long-range van der Waals interactions is emphasized. This manuscript, where two new complexes are synthesized and the H-bonding contacts individually estimated, is expected to attract the attention not only of synthetic inorganic chemists, but also theoreticians and chemists working in crystal engineering and supramolecular chemistry.

Approach to Di/Triorganotin(IV) Cations via Hydrolysis of Stannate Salts Bearing Alkanesulfonate Ligands

An in-depth study of the class of organotin cations bearing weakly coordinating trifluoromethanesulfonate/arylsulfonate has led to key insights into their stability, structural aspects, and role as catalysts. Related chemistry with alkanesulfonate ligands remains a missing link due to the strong Sn-O bond. The study reported herein describes the scope of diorganostannates, [n-Bu4N][R2Sn(OSO2R1)3] (R = n-Bu, R1 = Me(1), Et(2); R = Ph, R1 = Me(3)), as reactive substrates in the presence of adventitious water to afford [n-Bu2SnOH(OSO2Me)] (4), [n-Bu2Sn(H2O)4][n-Bu4N][OSO2Et]3·H2O (5), and [Ph2Sn(H2O)4][n-Bu4N]2[OSO2Me]4 (6), respectively, the latter two being the first examples of salt cocrystals comprising tetra(aqua)diorganotin cations. Hydrolysis of 3 in the presence of 1,4-bis((1H-imidazol-1-yl)methyl)benzene (bix) as the N-donor ligand proceeds via disproportionation and yields [Ph3Sn(bix)](OSO2Me) (7) along with an insoluble solid, likely derived from the hydrolysis of PhSn(OSO2Me)3. Direct evidence of this phenomenon can be gleaned from ESI-MS of 3, which identifies mass clusters corresponding to [Ph3Sn(OSO2Me)2]- and [PhSn(OSO2Me)3-H+]-. X-ray crystallographic studies of 1-7 are reported to establish their structural identity and the role of alkanesulfonate anions in the formation of supramolecular assemblies.

Multistep sequence-controlled supramolecular polymerization by the combination of multiple self-assembly motifs

The precise sequence control of polymer chain is an important research topic of polymer chemistry. Although some methods such as iterative synthesis and supramolecular polymerization have been developed to fabricate sequence-controllable polymer, it is still a great challenge to consecutively prepare multiple supramolecular polymers with different sequence structures. In this work, through the reasonable utilization of assembly motifs, we integrated multiple host-guest recognitions and metal coordination interactions to prepare different sequence-controlled supramolecular polymers by a multistep assembly strategy. This research provides inspiration for the design and preparation of supramolecular polymers with different sequence structures.