A 2D + 2D → 3D inclined polycatenated dynamic metal-organic framework of {[Cu(4-bpe)(2-ntp)(HO)]·2HO} [1, where 2-ntp = 2-nitroterephthalate and 4-bpe = 1,2-bis-(4-pyridyl)ethane] has been synthesized and characterized. The variable-temperature powder X-ray diffraction study indicates the dynamic nature of the inclined polycatenated framework, and the dehydrated framework with exposed metal centers exhibits excellent type I H adsorption of 1.94 wt % at 77 K and 1 bar of pressure.
Three different N,N′-donor ligands with Zn(NO 3 ) 2 •6H 2 O and two different dicarboxylates, flexible succinate (suc) and rigid fumarate (fum) afforded six different metal−organic frameworks (MOFs). Among the N,N′-donor ligands, one bent 1,4-bisHere, 3 is a pillared layer structure, whereas 4 has a 5-fold interpenetrated dimondoid network. For both the bent and straight N,N′-donor ligands an imine alike motif is embedded in the structure. When this motif is replaced by a C−C double bond by using the ligand 1,2-bis(4-pyridyl)ethylene (bpee), it produces two MOFs, {[Zn(bpee 6), having a similar structural relation like 3 and 4 respectively, 5 with a pillared layer structure and 6 with a 5-fold interpenetrated diamondoid network. All the compounds have been thoroughly characterized by powder X-ray diffraction (PXRD), elemental analysis, infrared (IR) spectroscopy, UV−vis spectroscopy, and thermogravimetric analyses. Gas/solvent vapor sorption studies have been carried out for compounds 3−6, which have 3D structures. In the case of 3, an interesting reversible crystalline to crystalline transformation was observed which has been thoroughly studied by PXRD analysis, IR spectroscopy, and UV−vis spectroscopy. Solid state emission spectral analysis for all the complexes was performed at room temperature.
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.
The broad applicability of the hitherto unexplored reagent combination PPh3·HBr-DMSO is exemplified with multiple highly diverse one-step transformations to synthetically useful building blocks, such as flavones, 4H-thiochromen-4-ones, α-hydroxy ketones, 1,4-naphthoquinones (including vitamin K3), 2-bromo-3-substituted-1H-1-indenones, 2-methylthio-1H-1-indenones, 3-butyne-1,2-dione, and 4-pentene-2,3-diones. The simple and mild reaction conditions make the reagent superior in terms of yield and substrate scope in comparison with the existing alternatives.
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