http://dspace.cus.ac.in/jspui/handle/1/6344 Thu, 16 Apr 2026 12:17:05 GMT 2026-04-16T12:17:05Z http://dspace.cus.ac.in/jspui/handle/1/6427 Title: Synthesis, structures and catalase activities of bis(μ-oxo)diMnIII,III and bis(μ- acetato)diMnII,II complexes bearing a quinolyl donor tripod ligand Authors: Biswas, Sachidulal; Das, Purak; Rasaily, Sagarmani; Pariyar, Anand; Biswas, Achintesh Narayan Abstract: The syntheses and characterization of two new complexes, [Mn2(TQA)2(µ-O)2](ClO4)2 (1) and [Mn2(TQA)2(µ-OAc)2](ClO4)2 (2) (TQA = tris(2-quinolylmethyl)amine), are described. The diMn complexes (1 & 2) have been characterized by elemental analysis, IR and X-ray diffraction. The complexes partly resemble the active-site structures of the oxidized and reduced forms of bacterial manganese catalases. Addition of aqueous H2O2 to the complexes in 1:1 MeOH/tris-buffer solution led to rapid evolution of O2 confirming their catalase activity. The complexes 1 & 2 exhibited turnovers of 810 and 665 mol O2 per mol of the catalysts, respectively. Catalytic efficiencies (kcat/KM) of 8.5 and 22 M−1 s−1 were measured for the complexes 1 & 2. The corresponding mononuclear Mn(II) complex, [Mn(TQA)(MeCN)(ClO4)](ClO4)·MeCN (3) also exhibited similar catalase activity. The complexes (1–3) showed marked preference for catalytic H2O2 disproportionation over oxidation of 2,2′-azinobis-(3-ethylbenzothiazoline)-6-sulfonicacid (ABTS). Tue, 01 Jan 2019 00:00:00 GMT http://dspace.cus.ac.in/jspui/handle/1/6427 2019-01-01T00:00:00Z http://dspace.cus.ac.in/jspui/handle/1/6354 Title: Temperature-Induced single-crystal-to-single-crystal transformations with consequential changes in the magnetic properties of Fe(III) complexes Authors: Adhikary, Amit; Akhtar, Sohel; Pariyar, Anand; Batsanov, Andrei S.; Mondal, Raju Abstract: The present article deals with an one-to-one structure−property correspondence of a dinuclear iron complex, [Dipic(H2O)- FeOH]2·H2O (1) (Dipic = pyridine-2,6-dicarboxylic acid). Variabletemperature X-ray single-crystal structural analysis confirms a phase transition of complex 1 to complex 2 ([Dipic(H2O)FeOH]2) at 120°C. Further, single-crystal-to-single-crystal (SCSC) transformation was monitored by temperature-dependent single crystal X-ray diffraction, powder X-ray diffraction, time-dependent Fourier-transform infrared spectroscopy, and differential scanning calorimetry. SCSC transformation brings the change in space group of single crystal. Complex 1 crystallizes in the C2/c space group, whereas complex 2 crystallizes in the Pi̅space group. SCSC transformation brings the change in packing diagram as well. Complex 1 shows two-dimensional network through H-bonding, whereas the packing diagram of complex 2 shows a zigzag-like arrangement. Phase transformation not only fetches structural changes but also in the magnetic properties. Difference in Fe−O−Fe bond angles of two complexes creates notable variation in their antiferromagnetic interactions with adjacent metal centers. Tue, 01 Jan 2019 00:00:00 GMT http://dspace.cus.ac.in/jspui/handle/1/6354 2019-01-01T00:00:00Z http://dspace.cus.ac.in/jspui/handle/1/6353 Title: Tetragonal versus hexagonal: structure-dependent catalytic activity of Co/Zn bimetallic metal−organic frameworks Authors: Pariyar, Anand; Asl, Hooman Yaghoobnejad; Choudhury, Amitava Abstract: Tetragonal and hexagonal phases of monometallic Zn and bimetallic Co/Zn metal–organic frameworks (MOFs), with secondary building units (SBUs) containing a M3O (M = metal) cluster, were synthesized from identical constituents using a benzenetricarboxylate (BTC3–) linker that forms decorated 3,6- and 3,5-connected networks, respectively. There exist subtle differences between the SBUs; one of the metal atoms in the M3O cluster in the tetragonal phase has one dissociable DMF solvent molecule while that in the hexagonal phase has three. Connectivities between the SBUs form one-dimensional channels in both MOFs. These MOFs catalyze the chemoselective addition of amines to epoxides, giving exclusively β-hydroxyamine under heterogeneous conditions. A ring-opening reaction of a symmetrical epoxide showed that the hexagonal phase diastereoselectively yields trans-alcohol, exhibiting an exquisite model for structure-dependent activity. Fri, 01 Jan 2016 00:00:00 GMT http://dspace.cus.ac.in/jspui/handle/1/6353 2016-01-01T00:00:00Z