Ap air of supramolecular isomers of Cd II -based MOF have been synthesized by utilizingaflexible N,N'-donor linker and ad icarboxylatew ith ESIPT (excited-state intramolecular proton transfer) fluorophore by varyingt he reaction media.O ne of the MOFs hasa3D four-fold interpenetrating framework with guests olventi nt he structure that undergoes as olvent-dependent crystalline-to-crystalline structural transformation, which has been extensively studied by powderX RD and IR spectroscopy.T he other MOF is structurally rigid in nature and has at wo-fold interpenetrating structure withouta ny guest molecules. Both the compounds show moderate CO 2 adsorption and one of them, the MOF with the four-fold interpenetrating structure, also shows moderately high H 2 adsorption.F urthermore, both the compounds show interesting luminescence behavior.I nt he solid state,t he two compounds show single-peak spectra,w hereas upon suspension of thesec ompounds in polar solvents, the maxima split into two peaks with al arge Stokes shift. On the other hand, in nonpolars olvents, only one emission maximumi so bserved. This solvatochromicd ual-emission phenomenon is due to ESIPT,w hich has been extensively studied.

Ligand based modification has been performed to synthesize a pair of mixed ligands d10 MOF based materials related to a previously published compound as a base material. The previous compound was a Zn­(II)-MOF, {[Zn­(4-bpdh)­(H2dht)]·(MeOH)­(H2O)} n (1) [N,N′-bis­(1-pyridin-4-yl-ethylidene)­hydrazine = 4-bpdh and 2,5-dihydroxyterephthalic acid = H4dht], which is a five-fold interpenetrated framework and highly dynamic in nature. In the first synthetic modification, the central metal is replaced by Cd­(II), which has the same framework formula as the base material, but this is a rigid compound and also there is no interpenetration in the framework. In the second modification, along with the metal center, the 4,4′-coordinating N,N′-donor ligand is replaced by an isomeric 3,3′-coordinating N,N′-donor linker. In this compound, the dynamism is regenerated. The dynamic nature can be realized by the extensive PXRD studies and characteristic “step-shaped” gas/solvent adsorption behavior for CO2, water, and ethanol. Furthermore, all these 3D MOFs show excited-state intramolecular proton transfer phenomena and water sensing properties in different organic solvents. Here excitingly, the ease of water sensing property is directly related to the dynamic behavior of the framework which has been studied thoroughly in terms of structural correlation.

Intriguing properties exhibited by porous coordination polymers (PCPs) have been discussed for a very long time, and the peak of the journey has been reached. Many ways have been introduced side by side to explore in the domain of PCPs with further progress to achieve various functionalities. Multifunctionality by these types of frameworks is one of those interesting features which has also been challenged to produce proper frameworks for exhibiting multiple properties by a single structure. Thus, after judicial choice of two different types of ligands, three coordination polymers {and {[Zn(1,4-(2-Me)-bix)(msuc)]•(solvent) x } n (4) have been synthesized and characterized. These three compounds along with one previously reported structurally similar complex {[Zn(1,4-(2-Me)-bix)(glu)]•4(H 2 O)} n (2) have been used to study gas sorption, electrical properties in dark and light, and luminescence. All the PCPs display different gas adsorptions (CO 2 , N 2 , H 2 ) and electrical conductance in both dark and illuminated conditions, which is an indication of multifunctionality shown by these structures. This designed structure and the measured properties of the synthesized complexes have been correlated with each individual framework of the four complexes based on the dicarboxylate flexibility/ substitution and the size of the metal ion.

No abstract

Two d10 metals complexes {[Zn2(fum)2(dim)2](H2O)(MeOH)}n (1) and {[Cd2(fum)2(dim)2(H2O)](MeOH)}n (2) have been prepared by using fumarate (fum) and di(1H-imidazol-1-yl)methane (dim) in methanol and water solutions. They have different structural architecture and...