Flexible luminescent non-lanthanide metal-organic frameworks as small molecules sensors

Toxic, carcinogenic, and hazardous materials are omnipresent, generally obtained by anthropogenic activities, industrial activities, aerobic and anaerobic degradation of waste materials and are harmful to human health and environment. Thus, sensing, colorimetric detection, and subsequent inclusion of these chemicals are of prime importance for human health and environment. In comparison to other classes of highly porous materials, luminescent metal-organic frameworks (LMOFs) have chromophoric organic ligands, high surface area, high degree of tunability and structural diversity. They have received scientific interest as sensory materials for device fabrication to detect and sense toxic small molecules. Especially, as soft-porous materials exhibiting a degree of flexibility or dynamic behaviour, flexible LMOFs are promising for selective detection and sensing, and for encapsulation of toxic and health hazardous molecules. Such flexible LMOFs offer a potential platform for selective adsorption/separation, molecular recognition, and sensing application. In this perspective, we highlight the advantages of flexibility of LMOFs for selective detection and sensing, and inclusion of toxic small molecules (solvents, anions, halobenzenes, aromatics, aromatic amines, nitro-explosives and acetylacetone). In addition, the principles and strategies guiding the design of these MOF based materials and recent progress in the luminescent detection of toxic small molecules are also discussed. In this perspective we limit our discussion on the 'non-lanthanide' based luminescent MOFs that have flexibility in the framework and show small molecule sensing applications.

Heterochiral Doped Supramolecular Coordination Networks for High-Performance Optoelectronics

Chiral self-sorting has great potential for constructing new complex structures and determining chirality-dependent properties in multicomponent mixtures. However, it is still of great challenge to achieve high fidelity chiral self-discrimination. Besides, the researches on the coordination polymers or metal-organic frameworks for micro/nanooptoelectronics are still rare due to their low conductivity and difficulty in developing a rapid and simple scale-up synthetic method. Here, heterochiral supramolecular coordination networks (SCNs) were synthesized by the solvothermal reaction of naphthalene diimide enantiomers and cadmium iodide, using the chirality as a synthetic tuning parameter to control the morphologies. Intriguingly, heterochiral micro/nanocrystals exhibited photochromic and photodetecting properties. Furthermore, we also developed a simple and efficient doping method to enhance the conductivity and photoresponsivity of micro/nanocrystals using hydrazine. From experimental and theoretical studies, the mechanism was suggested as follows: the radicals in the singly occupied molecular orbital level of the ligands provide charge carriers that can undergo "through-space" transport between π-π stacked ligands and the electron transfer from adsorbed hydrazine to the SCNs results in reduction of energy gap, leading to increased conductivity. Our findings demonstrate a simple and powerful strategy for implementing coordination networks with redox ligands for micro/nanooptoelectronic applications.

Cation⋯cation hydrogen bonds in synephrine salts: a typical interaction in an unusual environment

Computational studies of hydrogen-bonded cationic species observed in the synephrine salts point towards the stabilizing nature of hydrogen bonds and highlights their contribution in reducing destabilization caused by coulombic repulsion.

A Capped Dipeptide Which Simultaneously Exhibits Gelation and Crystallization Behavior

Short peptides capped at their N-terminus are often highly efficient gelators, yet notoriously difficult to crystallize. This is due to strong unidirectional interactions within fibers, resulting in structure propagation only along one direction. Here, we synthesize the N-capped dipeptide, benzimidazole-diphenylalanine, which forms both hydrogels and single crystals. Even more remarkably, we show using atomic force microscopy the coexistence of these two distinct phases. We then use powder X-ray diffraction to investigate whether the single crystal structure can be extrapolated to the molecular arrangement within the hydrogel. The results suggest parallel β-sheet arrangement as the dominant structural motif, challenging existing models for gelation of short peptides, and providing new directions for the future rational design of short peptide gelators.

Two chiral alkanolamine Schiff base Cu(ii) complexes as potential anticancer agents: synthesis, structure, DNA/protein interactions, and cytotoxic activity

Two novel chiral copper complexes have been synthesized and expressed DNA/protein binding strength and substantial cytotoxic activity.

Halide ion-driven self-assembly of Zn(ii) compounds derived from an asymmetrical hydrazone building block: a combined experimental and theoretical study

Self-assembly of Zn(ii) compounds is influenced by a counter ion and non-covalent interactions.

The role of weak hydrogen and halogen bonding interactions in the assembly of a series of Hg(ii) coordination polymers

A series of eight new Hg(ii) complexes based on the L^4-X ligands, where L is (E)-4-halo-N-(pyridin-4-ylmethylene)aniline, were synthesized and characterized and their supramolecular crystal structures were studied by different geometrical and theoretical methods.

Influence of noncovalent interactions on the structures of metal–organic hybrids based on a [VO2(2,6-pydc)]− tecton with cations of imidazole, pyridine and its derivatives

Hydrogen-bonding has a profound effect on topologies, and various 1D (band, pillar or chain), 2D and 3D hydrogen bonding networks have been observed.

A perception of ferro- and antiferromagnetic interactions in a two dimensional Ni(ii) heterochiral coordination polymer showing unusual CO2 uptake behavior

A robust 2D heterochiral Ni(ii) coordination polymer is reported which shows ferro-, antiferromagnetic interactions and unusual CO₂ uptake behavior.

Asymmetric allylation of sulfonyl imines catalyzed by in situ generated Cu(ii) complexes of chiral amino alcohol based Schiff bases

We have developed a catalytic route for enantioselective synthesis of homoallyl amines through Cu(ii)-Schiff base catalyzed allylation of aryl N-sulfonylimines.

Homologous 1,3,5-triarylpyrazolines: synthesis, CH⋯π interactions guided self-assembly and effect of alkyloxy chain length on DNA binding properties

The synthesis, CH⋯π interactions-driven self-assembled structure and DNA binding properties (10⁵–10⁶M⁻¹binding constants) of new homologous 1,3,5-triaryl-2-pyrazolines are reported.

Potential apoptosis inducing agents based on a new benzimidazole schiff base ligand and its dicopper(ii) complex

Synthesis, characterization and DNA/protein binding studies of new benzimidazole based dicopper(ii) complex inducing apoptosis in MCF-7 cells have been presented.