Supramolecular Architectures Research Articles

Crystal structure of the heterometallic complex of Co(II) and Nd(III) with phenanthroline

A new heterometallic complex of CoII and NdIII with phenathroline [Co(Рhen)3][Nd(NO3)5(H2O)][Nd(NO3)4(H2O)2]H2O was synthesized for the first time by the self-assembly method. The crystal structure of the complex was determined by X-ray crystallography. The compound is an anion-cation complex and crystallizes in the monoclinic space group P21/n with unit cell parameters a=12.4251(4) Å, b=11.7206(3) Å, c=36.5374(12) Å, ==900, =90.581(3)0. In the crystalline phase, the complex is in the form of a crystal hydrate with a composition of 1:1. The anionic part of the complex consists of two nitrate hydrated NdIII complexes: [Nd(NO3)5(H2O)]2– and [Nd(NO3)4(H2O)2]–, in which the coordination number of neodymium is 11 and 10, respectively. The [Co(Phen)3]3+ ion is a cationic part of the complex in which the CoII atom has a distorted CoN6 octahedral environment, bidentately coordinating three phenanthroline molecules. Due to intermolecular hydrogen bonds (N–HO, O–HO), a three-dimensional supramolecular architecture is formed in the crystal, in which the polymer layers are packed parallel along the crystallographic axis a.

Understanding the Role of NHC Ditopic Ligand Substituents in the Molecular Diversity and Emissive Properties of Silver Complexes.

Silver bis(carbene) complexes featuring ditopic N-heterocyclic carbene (NHC) ligands have been synthesized which enable the assembly of supramolecular architectures via reaction with silver triflate. Through a systematic exploration of crystal structures and emissive properties, this study investigates the impact of the substituents on the NHC ditopic ligands [R-Im-2-Z-py], where R = Me, benzyl (Bz), or 2-naphthylmethyl (NaphCH2), and Z = H or Cl in the structural framework and emissive properties observed in the silver bis(carbene) or polynuclear species. Remarkably diverse structural motifs emerge in both of them, predominantly influenced by the choice of R wingtip and second by the Z substituent. Also the emissive quantum yield of the complexes is mostly governed by the selection of the R wingtip and further modulated by the Z substituent. Several of the mono and polynuclear complexes exhibit complex emissive profiles, including the observation of dual emission phenomena. Particularly noteworthy is the complex [Ag(NHC)]2]OTf (R = Bz, Z = Cl), which demonstrates an exceptionally intense single blue emission with a remarkable solid-state quantum yield (Φ) of 24%.

Switchable pH-Responsive Morphologies of Coassembled Nucleobase Copolymers.

This work presents supramolecular coassembled nucleobase copolymers with transitional morphologies upon pH changes (from 7.4 to 10). Uracil- and adenine-containing copolymers were prepared by RAFT, which allowed us to finely tailor the polymerization degree and the composition. The coassembled formulations prepared in an aqueous buffer at two distinct pH (7.4 and 10) formed spherical morphologies at physiological pH. The increase of the pH induced the apparition of various large, irreversible anisotropic supramolecular architectures. Isothermal titration calorimetry revealed that the coassembly at pH 7.4 was mainly guided by H-bonds between complementary nucleobases, while the experiments conducted at pH 10 showed that the assemblies were mainly driven by hydrophobic interactions. These results highlight that the nature of supramolecular interactions (H-bonds or hydrophobic interactions) has a great influence on the morphology of nucleobase-containing coassemblies when changing the pH. These findings may provide further perspectives in the field of advanced nanomaterials.

From Double-Stranded Helicates to Abiotic Double Helical Supramolecular Assemblies.

The folding of oligomeric strands is the method that nature has selected to generate ordered assemblies presenting spectacular functions. In the purpose to mimic these biomacro-molecules and extend their properties and functions, chemists make important efforts to prepare artificial secondary, tertiary, and even quarternary structures based on folded abiotic backbones. A large variety of oligomers and polymers, encoded with chemical informations, were designed, synthesized and characterized, and the establishment of non-covalent interactions lead to complex and functional supramolecular architectures resulting from a spontaneous self-assembly process. The association of comple-mentary molecular strands into double helical structures is a common structural pattern of nucleic acids and proteins, so the synthesis of bio-inspired double helices has emerged as an important subject. In recent years, a number of synthetic oligo-mers have been reported to form stable double helices and it was shown that the equilibrium between single and double helices can be controlled via different stimuli like the modification of the solvent or the temperature. This kind of structure presents highly interesting functions, such as molecular recognition within the cavity of double helices, and some other potential applications will emerge in the future.

Synthesis, crystal structure, Hirshfeld surface analysis, DFT computations and protein binding efficiency of a 1-D Ni(II) chain derived from a tridentate Schiff base ligand

A new Ni(II)-azido 1-D coordination polymer, [Ni2L2(μ1,1-N3)(μ1,3-N3)]n, was obtained through reaction of 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) and the perchlorate salt of nickel(II) in the presence of pseudohalide azide. X-ray crystallography and spectroscopic experiments (IR and UV-Vis) were used to describe this coordination polymer (CP). Single crystal X-ray studies revealed that the CP is a one-dimensional chain of Ni(II) in which the neighboring dimeric units (triply bridged by di-μ2-phenoxidoand µ1,1-N3) are further connected by μ1,3-azido bridges in a zig-zag fashion. The cooperative participation of N···H hydrogen bonding, π···π stacking and C-H···π interactions occur during crystal packing. A 2-D supramolecular architecture with star-shaped voids results from additional C–H···π stacking interactions. Hirshfeld surface analysis was used to look at the intermolecular interactions. DFT studies were carried out to calculate the HOMO-LUMO band gap of the ligand as well as the coordination polymer. Interaction of the CP with bovine serum albumin (BSA) protein was investigated spectroscopically by absorption and fluorescence titration methods. The result showed that the CP could quench the intrinsic fluorescence of BSA. Fluorescence resonance energy transfer (FRET) studies revealed that energy transfer takes place from BSA to the CP. Cyclic voltammetry of the CP indicated an irreversible cathodic redox couple assigned to Ni(II)/Ni(I).

Structural Characteristics and DNA Groove Binding Abilities of Two Zinc BasedIsoreticularMOFs.

In this study, we have synthesized two zinc(II)-based metal-organic frameworks (MOFs) designated as [Zn(4-nvp)(bdc)]·(MeOH) (1) and [Zn2(4-nvp)2(bpdc)2]·(DMF) (2) [4-nvp = 4-(1-Naphthylvinyl) pyridine, H2bdc = 1,4-benzendicarboxylic acid and H2bpdc = 4,4'-biphenyldicarboxylic acid]. Single-crystal X-ray diffraction (SCXRD) of both compounds unveiled an interesting paddle-wheel [Zn2(O2C-C)4] secondary building unit composed of dinuclear Zn (II) centers and four dicarboxylate groups with a (4,4) square grid topology. These SBUs are interconnected giving rise to an infinite 2D layer architecture. Notably, the grid structure is composed of MeOH molecules in compound 1 and DMF molecules in compound 2, both of them arranged in a free lattice. In both compounds, 3D supramolecular architecture is ultimately formed through the stacking of 2D layers. Since the length of the bpdc ligand is higher than that of the bdc ligand, the solvent-accessible void volume is comparatively higher for compound 2. To corroborate all non-bonded interactions, Hirshfeld analysis was carried out for synthesized compounds. DNA binding application was extensively investigated through docking study. Results indicated that the synthesized compounds have strong affinities towards DNA via DNA groove binding. Henceforth, the synthesized compounds 1 and 2 would open the door for their potential applications as particular protein binders and bioactive substances.

Hydrogen-bonding interactions in the salts 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, 2,4,6-triaminopyrimidin-1-ium N-phenylantharanilate and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate.

Three salts, namely, 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, C4H8N5+·C6H7O2-·2H2O, (I), 2,4,6-triaminopyrimidin-1-ium N-phenylanthranilate, C4H8N5+·C13H10NO2-, (II), and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate, C4H8N5+·C7H7O3S-, (III), were synthesized, characterized by X-ray diffraction techniques and their supramolecular interactions investigated. In all three crystal structures, protonation of the pyrimidine moiety occurs at the N1 position and is reflected in a widening of the C-N-C bond angle. In salts (I)-(III), the primary acid-base interaction occurs through a pair of N-H...O hydrogen bonds to give a heterodimeric R22(8) synthon. Salts (II) and (III) form a discrete centrosymmetric base pair that produces a homodimeric R22(8) synthon and salt (I) forms a water-mediated base pair resulting in a tetrameric R44(12) synthon. The supramolecular patterns exhibited by sulfonate salt (III) mimic the patterns of carboxylate salt (II) and both exhibit a DADA array (D = donor and A = acceptor) quadruple hydrogen-bonded pattern. The crystal structures of salts (I) and (III) are stabilized by offset and face-to-face aromatic π-π stacking interactions, respectively. The resulting architectures in salts (I)-(III) are a supramolecular sheet with a rosette-like architecture in (I), a supramolecular sheet-like architecture in (II) and a three-dimensional supramolecular network in (III).

Storehouse of Peculiar Supramolecular Architecture: Probing the Charge-Transfer Phenomenon and Effect of Altering the pH in a Meta-Oriented Single Donor-Double Acceptor Fluorophore.

The investigation of excited-state intramolecular charge transfer (ESICT) has been a fascinating area of research. Although the ESICT events have been studied mostly for para-disubstituted donor-acceptor type molecules, the meta-oriented donor-acceptor type molecules have also shown tremendous potential as ESICT active molecules. In the current work, a small fluorescent probe diethyl 5-amino isophthalate (DE-5A-IPA) was investigated as a potential model to investigate ESICT events in the solution as well as solid phase. DE-5A-IPA was synthesized easily starting from commercially available 5-amino isophthalic acid in excellent yield. In the solid state, differing extents of CH···π-type binding led to formation of fully planar and puckered "cyclobutane" mimic supramolecular architecture, as evidenced from the crystal structure analysis. In addition, the single crystal structure of DE-5A-IPA shows that the donor (-NH2) and acceptor (-CO2Et) are situated in the same plane, thereby assuring the prerequisites of a through-space charge transfer. DE-5A-IPA undergoes noticeable Stokes shift (in cm-1) when the polarity of the medium was changed (4820 cm-1 in hexane; 9375 cm-1 in water). The excited-state dipole moment (μe) was calculated to be 4.0 units higher than the ground-state dipole moment (μg). DE-5A-IPA had an appreciable quantum yield (0.10 ± 0.03 to 0.27 ± 0.04). The ESICT phenomenon was also investigated by ground- and excited-state structural calculations using Gaussian 16 software. The excited-state lifetime measured by the time correlated single photon counting technique was found to vary with the polarity of the solvent, thereby providing further support to the ESICT phenomenon being operative in DE-5A-IPA. Taking advantage of the -NH2 group (which is susceptible to protonation) in DE-5A-IPA, steady state and time-resolved photodynamics were investigated in solutions of varying pH values. Interestingly, the emission quantum yields as well as the emission lifetime increase with an increase in pH value, thereby establishing DE-5A-IPA as a pH-sensitive probe. The current findings shall boost the understanding of meta-oriented ESICT enabled compounds in terms of their excited-state photophysics.

Structural insights into supramolecular interactions in isostructural salts of 2,4,6-triaminopyrimidinium with various heterocyclic carboxylates.

2,4,6-Triaminopyrimidine is an interesting and challenging molecule due to the presence of multiple hydrogen-bond donors and acceptors. Its noncovalent interactions with a variety of carboxylic acids provide several supramolecular aggregates with frequently occurring molecular synthons. The present work focuses on the supramolecular interactions of 2,4,6-triaminopyrimidinium 3-(indol-3-yl)propionate-3-(indol-3-yl)propionic acid (1/1), C4H8N5+·C11H10NO2-·C11H11NO2, (I), 2,4,6-triaminopyrimidinium 2-(indol-3-yl)acetate, C4H8N5+·C10H8NO2-, (II), 2,4,6-triaminopyrimidinium 5-bromothiophene-2-carboxylate, C4H8N5+·C5H2BrO2S-, (III), and 2,4,6-triaminopyrimidinium 5-chlorothiophene-2-carboxylate, C4H8N5+·C5H2ClO2S-, (IV). All four salts exhibit robust homomeric and heteromeric R22(8) ring motifs. Salts (I) and (II) develop sextuple [in (I)] and quadruple [in (I) and (II)] hydrogen-bonded arrays through fused-ring motifs. Salt (II) exhibits a rosette-like architecture. Salt (IV) is isostructural and isomorphous with salt (III), exhibiting an identical crystal structure with a different composition and an identical supramolecular architecture. In salts (III) and (IV), a linear hetero-tetrameric motif is formed and, in addition, both salts exhibit halogen-π interactions which enhance the crystal stability. All four salts develop a supramolecular hydrogen-bonded pattern facilitated by several N-H...O and N-H...N hydrogen bonds with multiple furcated donors and acceptors.

Sensitive Detection and Visual Recognition of Jatrorrhizine Based on a Fluorescent Eu Coordination Polymer Probe

ABSTRACTBased on 4‐([2,2′:6′,2″‐terpyridin]‐4′‐yl) benzoic acid ligand (Htpba), a fluorescent lanthanide coordination polymer was successfully synthesized, namely, [Eu (tpba)3]n (1). The single‐crystal diffraction analysis shows that Eu3+ ions in complex 1 are alternately connected with tpba3− ligands to form a one‐dimensional chain structure, which further constitutes a three‐dimensional supramolecular architecture through the π···π interactions. Complex 1 demonstrated excellent stability of thermogravimetry; and displayed good fluorescence intensity in aqueous solution with a wide pH range. In this work, complex 1 was used as a fluorescence sensor for the detection of jatrorrhizine molecule (JAT). It was found that complex 1 had high sensitivity with the detection limit of 1.02 × 10−8 M, and simultaneously displayed specific selectivity and reutilization for the exploration of JAT molecule. The static quenching, the absorption competition, the electrostatic interactions, and the photo‐induced electron transfer process are responsible for the recognition mechanism of complex 1 with sensing JAT. It is worth mentioning that a fluorescent film based on complex 1 and a light‐emitting diode device coated with the powder of complex 1 were successfully fabricated, which could rapidly recognize JAT molecule with the naked eye further.

Heteronuclear cadmium(II)/cobalt(III) cyanide coordination polymers with 1-methylimidazole and 1-ethylimidazole ligands: synthesis, characterization and catalytic activities

Two new heteronuclear Cd(II)/Co(III) compounds, {[Cd(1-meim)3Cd0.5(1-meim)Co(μ-CN)4(CN)2]}n (1) and {[Cd(1-etim)3Cd0.5(1-etim)2Co(μ-CN)3(CN)3]⋅H2O}n (2) (1-meim: 1-methylimidazole, 1-etim = 1-ethylimidazole), have been synthesized and characterized using elemental analysis, FT-IR and Raman spectroscopy, single-crystal X-ray diffraction techniques. The single crystal X-ray study shows that the compound 1 exhibited a 1D double chain structure and is further linked into 3D supramolecular architectures through CH⋅⋅⋅N and π⋅⋅⋅π interactions. Whereas the compound 2 displayed 2D network which is extended into a 3D supramolecular framework by OH⋅⋅⋅N hydrogen bonds and CH∙∙∙π interactions. In 1 and 2, each Co(III) ion is coordinated by six carbon atoms from cyanide ligands, thus showing an octahedral coordination geometry. Cd1 and Cd2 ions exhibited two different geometries, distorted trigonal bipyramidal and octahedral. Furthermore, phase purities, catalytic and thermal properties were investigated.

Synergistic effect of hydrogen bonding and C–H…π interactions to modulate the supramolecular assemblies of isobenzofuranones: X-ray crystallography, DFT analysis and antihyperglycemic potential

This manuscript reports the synthesis, X-ray characterization and antihyperglycemic potential of two isobenzofuranone derivatives. The Suzuki-Miyaura cross-coupling of 5-bromoisobenzofuran-1(3H)-one with phenylboronic acid and p-tolylboronic acid under the action of palladium catalysis afforded the desired compounds in good yields. The structures were fully established using FTIR and NMR spectroscopy and X-ray crystallography. The study further delves into the synergistic effects of hydrogen bonding and C–H…π interactions on the supramolecular assemblies of isobenzofuranones, leveraging a holistic approach that combines X-ray crystallography, Density Functional Theory (DFT) analysis, and evaluation of antihyperglycemic activity. Focusing on two isobenzofuranone derivatives, we meticulously elucidate their structural features and how noncovalent interactions shape their crystal packing. Our exploration extends to assessing the antihyperglycemic potential of these compounds, underpinned by α-glucosidase inhibitory assays and augmented by molecular docking analysis. Compound 3b showed the best potency with an IC50 value of 13 ± 0.01 µM which is 67-folds strong inhibition than acarbose (IC50 = 870.2 ± 1.54 µM). Furthermore, the admetSAR and ProTox-II demonstrated that compound 3b follows the druggable criteria with a safe toxicity profile. Overall, these findings highlight the pivotal role of noncovalent interactions in modulating the supramolecular architectures of isobenzofuranones, thereby offering insights into their therapeutic potential against diabetes mellitus.

An experimental and computational investigation of the cyclopentene-containing peptide-derived compounds: focus on pseudo-cyclic motifs via intramolecular interactions.

Conformational flexibility is one of the main disadvantages of peptide-based compounds. We focus on their molecular 'chameleonicity' related to forming pseudo-cyclic motifs via modulation of weak intramolecular interactions. It is an appealing strategy for controlling equilibrium between the polar open and the nonpolar closed conformations. Within this context, we report here the crystal structure of the (R)-(2-tert-butoxycarbonyl)amino-1-oxo-3-phenyl)propyl)-1-cyclopentene (1), synthesis of which in high yield was achieved by a facile multi-step protocol. Our Cambridge Structural Database (CSD) overview for the peptide-based crystals revealed the exclusivity of this compound from the viewpoint of the unusual pseudo-bicyclic system via C-H…O and C-O…π interactions, in which cyclopentene shields the amide bond. Notably, cyclopentene as a bioisostere of proline is an appealing scaffold in medicinal chemistry. An extensive combined experimental and computational study provided more profound insight into the supramolecular landscape of 1 with respect to similar derivatives deposited in the CSD, including the tendency of cyclopentene for the generation of pseudo-cyclic motifs through weak H-bonding and π-based intramolecular interactions. These weak interactions have been examined by either the quantum theory of 'atoms-in-molecules' (QTAIM) or complex Hirshfeld surface methodology, including enrichment ratios, molecular electrostatic potential surfaces and energy frameworks. In all analysed crystals, all types of H-bonded motifs involving cyclopentene are formed at all levels of supramolecular architecture. A library of cyclopentene-based H-bonding synthons is provided. A molecular docking study depicted vital interactions of cyclopentene with key amino acid residues inside the active sites of two prominent protein kinases, uncovering the therapeutic potential of 1 against breast cancer. To a large extent, dispersion forces have significance in stabilizing the supramolecular structure of both ligand and bio-complex ligand-protein. Finally, the satisfactory in silico bio-pharmacokinetic profile of 1 related to drug-likeness and blood-brain barrier permeation was also revealed.

Supramolecular Architectures of Dendritic Polymers Provide Irreversible Inhibitor to Block Viral Infection.

In Nature, most known objects can perform their functions only when in supramolecular self-assembled from, e.g. protein complexes and cell membranes. Here, a dendritic polymer is presented that inhibits severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with an irreversible (virucidal) mechanism only when self-assembled into a Two-dimmensional supramolecular polymer (2D-SupraPol). Monomeric analogs of the dendritic polymer can only inhibit SARS-CoV-2 reversibly, thus allowing for the virus to regain infectivity after dilution. Upon assembly, 2D-SupraPol shows a remarkable half-inhibitory concentration (IC50 30nM) in vitro and in vivo in a Syrian Hamster model has a good efficacy. Using cryo-TEM, it is shown that the 2D-SupraPol has a controllable lateral size that can be tuned by adjusting the pH and use small angle X-ray and neutron scattering to unveil the architecture of the supramolecular assembly. This functional 2D-SupraPol, and its supramolecular architecture are proposed, as a prophylaxis nasal spray to inhibit the virus interaction with the respiratory tract.

Programmable Reconfiguration of Supramolecular Bottlebrush Block Copolymers: From Solution Self-Assembly to Co-Crystallization-Assistant Self-Assembly.

Achieving structural reconfiguration of supramolecular bottlebrush block copolymers toward topological engineering is of particular interest but challenging. Here, we address the creation of supramolecular architectures to discover how assembled topology influences the structured aggregates, combining hydrogen-bonded (H-bonded) bottlebrush block copolymers and electrostatic interaction induced polymer/inorganic eutectics. We first design H-bonding linear-brush block copolymer P(NBDAP-co-NBC)-b-P(NBPEO), bearing linear block P(NBDAP-co-NBC) (poly(norbornene-terminated diaminopyridine-co-norbornene-terminated hexane)) with pendant H-bonding DAP (diaminopyridine) motifs, and PEO (poly(ethylene oxide)) densely grafted P(NBPEO) brush block. Thanks to H-bonding association between DAP and thymine (Thy), incorporation of Thy-functionalized polystyrene (Thy-PS65) enables solution self-assembly and formation of H-bonded bottlebrush block copolymers, generating augmented nanospheres with increasing Thy-PS65 amount. Noteworthy that integration of inorganic cluster silicotungstic acid (STA) to P(NBC-co-NBDAP)-b-P(NBPEO), endows the formation of PEO/STA eutectic core. Therefore, co-crystallization-assistant self-assembly at the interfaces of polymeric, inorganic and supramolecular chemistry is realized, reflecting multi-stage morphology transformation from hexagonal platelets, needle-like, curved rod-like micelles, finally to end-to-end closed rings, by gradually increasing Thy-PS65 while fixing STA content. Interestingly, such solution self-assembly to co-crystallization-assistant self-assembly strategy not only endows unique nanostructure transition, also induce in-to-out reconfiguration of PS domains. These findings clearly provide unique methodology towards programmable fabrication of geometrical objects promising in smart materials.

In Situ Ligand-Transformation-Assisted Assembly of a Polyoxometalate and Silver-Phosphine Oxide Cluster for Colorimetric Detection of Phenol Contaminants.

In situ ligand transformation strategies represent an efficient pathway for constructing function-oriented polyoxometalate (POM)-based crystalline materials. Herein, three POM-based hybrid networks were synthesized through in situ transformation of the phosphine ligand, formulated as [Ag(dppeo)6][H2PMo12O40]·5H2O (1), [Ag(dedpo)]4[SiW12O40]·6H2O (2), and [Ag(dppeo)]3[PW12O40]·3H2O (3) (dedpo = (2-(diphenylphosphaneyl)ethyl)diphenylphosphine oxide; dppeo = ethane-1,2-diylbis(diphenylphosphine oxide)). During the synthesis of these compounds, the 1,2-diphenylphosphine ethane molecule underwent in situ oxidation, transforming into dppeo and dedpo ligands, respectively. Compound 1 features a supramolecular architecture assembled from [Ag(dppeo)3]+/[Ag2(dppeo)6]2+ cationic clusters with disordered Ag centers and protonated [H2PMo12O40]- anions. Compound 2 presents a 3-D POM-supported metal-organic framework consisting of binuclear [Ag(dedpo)]22+ units, {-dedpo-Ag-dedpo-} chains, and [SiW12O40]4- polyoxoanions. Compound 3 displays a 2-D layered structure formed by {-dppeo-Ag3-dppeo-} chains and [PW12O40]3- clusters. Pronounced argentophilic interactions are observed in compounds 1 and 3. The three compounds demonstrate satisfactory heterogeneous catalytic activity in the colorimetric detection reactions toward phenol pollutants with detection limits of 1.73, 1.92, and 4.6 μM, respectively. Additionally, compounds 1-3 show high anti-interference capabilities and high sensitivity in differentiating phenol from its halogenated derivatives. This work presents some guidance for designing specific function-oriented POM-based materials via an in situ ligand transformation strategy.

Synthesis, crystal structure, spectral analysis and NLO studies of five-coordinate Zn(II) complexes of hydrazochromandione

Using a hydrazochromandione ligand, a straightforward chemical process is used to create zinc(II) complexes (1 and 2) with five coordination. Elemental microanalysis and a range of spectroscopic techniques (FT-IR, 1H NMR and electronic spectroscopy) were used to characterize the ligand and Zn(II) complexes. Single crystal X-ray diffraction was used to identify the crystal structures of HL, complex 1 and 2, and the results showed that ligand has monoclinic system with centrosymmetric space group P21/n. Through ONO donor atoms, Zn(II) metal is coordinated to the ligand in the same way as monoanionic. Two Zn(II) complexes with a deformed square pyramidal geometry surrounding them. Interestingly, relatively strong hydrogen bonds and p-p interactions that result in supramolecular architectures preserve the stabilization of the crystal lattices. Comparing two Zn(II) complexes to hydrazochromandione ligand, they exhibit good non-linear optical response.

Structural Diversity and Dimensionality of Three Cu(II)-dpds-C5O5 2- Coordination Polymers Controlled by the Coordination Sphere of Cu(II) Centers and the Coordination Modes of C5O5 2- (dpds = 4,4'-Dipyridyldisulfide).

Three supramolecular architectures, [Cu2(dpds)2(C5O5)2(H2O)4]·3H2O (1), [Cu(dpds)(C5O5)]·3H2O (2), and [Cu2(dpds)2(C5O5)2]·9H2O·C2H5OH (3) (dpds = 4,4'-dipyridyldisulfide and C5O5 2- (croconate) = dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione), have been synthesized and structurally characterized. Compound 1 contains two crystallographically independent Cu(II) ions, which are both distorted octahedral geometry with elongation along the croconate- and H2O-bound axial positions and bonded with two N atoms of two dpds, two O atoms of one C5O5 2-, and two H2O molecules. Two crystallographically independent dpds ligands, both adopting the bis-monodentate bridging mode, connect two Cu(II) ions to form a one-dimensional zigzag chain-like coordination polymer. In 2 and 3, there are two and three crystallographically independent Cu(II) ions, respectively, which are all distorted octahedral geometries with elongation along the croconate-bound axial positions six-coordinated and bonded with two N atoms of two dpds ligands in cis- or/and trans-forms and four O atoms of two C5O5 2- ligands. The dpds ligands in 2 and 3 all adopt the bis-monodentate bridging mode, and the C5O5 2- ligands act as bridging ligands with bridging bis-bidentate through three C5O5 2- oxygen atoms in 2 and bridging bis-bidentate through four adjacent C5O5 2- oxygen atoms in 3, respectively, linking the Cu(II) ions to generate a two-dimensional layered and a three-dimensional metal-organic framework, respectively. The structural diversity and dimensionality observed in 1-3 may be attributed to the cis- or/and trans-coordination sphere of Cu(II) centers with two dpds ligands and the coordination modes of croconate ligands. Thermal stability and in situ temperature-dependent structural variations of 1-3 have been verified by thermogravimetric analysis and powder X-ray diffraction measurements. Compounds 1 and 3 both exhibit water vapor capture behaviors with hysteresis isotherms.

Terpyridine-Based Metal-Organic Cage with Enhanced Emission via Coordination-Induced Rigidity.

Realizing the regulation of photophysical properties by precisely controlling the molecular composition and configuration, thereby obtaining high-performance optical materials, remains of great significance. Due to the directionality and reversibility of the coordination bond, coordination-driven self-assembly endows the molecule with customized thermodynamically stable structures and desired properties. In this paper, a luminous metal-organic cage [Zn12L6] (S) was elaborately designed and quantitatively synthesized by self-assembly of tetrapodal TQPP chromophore-containing terpyridine ligand L with Zn2+. Complex S possessed a rigid cage-like structure, which endows a higher fluorescence quantum efficiency both in solution (∼88%) and neat solid (16%) than the corresponding ligand L. Further, using complex S as the photoactive component, two light-emitting diodes (LEDs) were successfully fabricated and the emission of pure white light (CIE coordinates: 0.3341, 0.3300) was achieved. These results afford a method to obtain enhanced luminescence performance via the formation of rigid coordination-driven supramolecular architectures.

Four compounds containing 1-(2-carboxyethyl)-4,4′-bipyridine: Synthesis, crystal structure and chromic behavior

Herein, four compounds containing the neutral viologen derivative, 1-(2-carboxyethyl)-4,4′-bipyridine (CBbpy) have been synthesized, (CBbpy)·(H2TPDC)·H2O (1), [Co0.5(CBbpy)(H2O)2](HTPDC)·2 H2O (2), [Ni0.5(CBbpy)(H2O)2](HTPDC)·2 H2O (3) and {[Cd(CBbpy)2(H2O)2][Cd(TPDC)2]·4 H2O}n (4) (H2TPDC = thiophene-2,5-dicarboxylic acid). Compound 1 is a co-crystal that forms the donor-acceptor (D-A) system through non-covalent interactions. Compounds 2 and 3 own the same isolated structure, in which metal ions coordinate with CBbpy to form cations, while H2TPDC loses a proton to form anions. Compound 4 contains one-dimensional (1D) {[Cd(CBbpy)2(H2O)2]2+}n double chain and two-dimensional (2D) {[Cd(TPDC)2]2-}n layer, which leads to a 1D + 2D→three-dimensional (3D) interdigitated supramolecular architecture. Although four compounds comprise the same bipyridinium moiety, their chromic behaviors are different. Compounds 1 and 4 own reversible photochromic action, while 2 and 3 reveal hydrochromic action upon heating. Based on the photochromic properties of 1 and 4, the photo-modulated fluorescence and the potential applications of inkless and erasable printing are investigated.