Author
Muktimoy Chaudhury
Bio: Muktimoy Chaudhury is an academic researcher from Indian Association for the Cultivation of Science. The author has contributed to research in topics: Ligand & Octahedral molecular geometry. The author has an hindex of 25, co-authored 81 publications receiving 1818 citations.
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TL;DR: In this paper, the mononuclear oxovanadium complexes [VVOL(OR)] (R: Me, 1a; Et, 1b; Pri, 1c) and [VIVOLB] (B: Im, 2a; BzIm, 2b) were characterized by various physical techniques, including 1H NMR, EPR, and cyclic voltammetry.
Abstract: The mononuclear oxovanadium complexes [VVOL(OR)] (R: Me, 1a; Et, 1b; Pri, 1c) and [VIVOLB] (B: Im, 2a; BzIm, 2b) of the tridentate ONS donor ligand S-methyl 3-((2-hydroxyphenyl)methyl)dithiocarbazate (H2L) are reported. The novel mixed-valence (μ-oxo)divanadium(IV,V) complex (BzImH)[(LVO)2O] (3) was synthesized using 1a and 2b as precursors. All of the complexes were characterized by various physical techniques, including 1H NMR, EPR, and cyclic voltammetry. The X-ray structures of 1a and 3 were determined. Crystals of 1a are triclinic, of space group P1, with a = 11.045(1) A, b = 13.429(4) A, c = 9.611(1) A, α = 100.00(1)°, β = 114.33(1)°, γ = 81.00(1)°, and Z = 4. The asymmetric unit of 1a contains two independent molecules with minor conformational differences. Crystals of 3 are monoclinic, of space group P21/n, with a = 10.10(1) A, b = 20.594(9) A, c = 14.679(8) A, β = 95.28(6)°, and Z = 4. 3 is a bent molecule, with a V−O−V bridge angle of 144.0(6)°. It has a trapped-valence structure in the solid...
86 citations
TL;DR: In order to study the reactivity pattern of Mo−Ot bonds associated with anionic sulfur ligands, precursor complexes MoO2L·D (H2L = S-methyl 3-(2-hydroxyphenyl)methylenedithiocarbazate; D = CH3OH (1), H2O (2)) were synthesized as discussed by the authors.
Abstract: In order to study the reactivity pattern of Mo−Ot bonds associated with anionic sulfur ligands, precursor complexes MoO2L·D (H2L = S-methyl 3-(2-hydroxyphenyl)methylenedithiocarbazate; D = CH3OH (1), H2O (2)) were synthesized. Complex 2 crystallizes in the orthorhombic space group P212121, with a = 6.079(1) A, b = 11.638(2) A, c = 17.325(2) A, V = 1225.7(4) A3, and Z = 4. In its reaction with PhNHOH, 1 forms a seven-coordinate oxaziridine compound [MoO(η2-ONPh)L·CH3OH] (3) by oxo-rearrangement (elimination−substitution) without a change in the molybdenum oxidation state. The crystal data for 3 are a = 9.573(3) A, b = 9.859(2) A, c = 10.604(3) A, α = 95.90(2)°, β = 95.81(2)°, γ = 112.12(2)°, V = 911.5(4) A3, Z = 2, and triclinic space group P1. In contrast to that of the precursor compound 1 (Mo−Ot = 1.700(4) A), the terminal Mo−Ot distance in 3 (1.668(2) A) is typical of Mo−O bonds of order 3, which drives the formation of an apparently unstable three-membered metallacycle via spectator oxo stabilization...
83 citations
TL;DR: In this paper, the molecular structures of [Zn(mmpcd)]ClO4 (1b) and [Cu(mpcd]ClO 4 (2b) were refined to final R = 0.042 for 1b and 0.049 for 2b.
Abstract: Zinc(II) and copper(II) complexes of two new potentially pentadentate ligands based on methyl 2-aminocyclopent-1-ene-1-dithiocarboxylate with pendent pyrazolyl groups (Me2pzCH2)2NC2H3RNHC5H6CSSCH3 (R = H, Hmmecd, and R = CH3, Hmmpcd, both having N4S donor atoms set) have been reported. The molecular structures of [Zn(mmpcd)]ClO4 (1b) and [Cu(mmpcd)]ClO4 (2b) show a distorted trigonal bipyramidal geometry for the Zn(II) ion and a square pyramidal geometry for the Cu(II) ion. 1b crystallizes in the triclinic space group P1, a = 9.900(3) A, b = 15.379(5) A, c = 8.858(2) A, α = 99.93(2)°, β = 93.62(2)°, γ = 100.38(2)°, V = 1300.5(7) A3, and Z = 2; while 2b crystallizes in the monoclinic space group P21/n, a = 12.859(6) A, b = 12.642(3) A, c = 16.503(2) A, β = 102.67(2)°, V = 2617(1) A3, and Z = 4. The structures were refined to final R = 0.042 for 1b and 0.049 for 2b. The EPR and electronic spectroscopic studies showed that the copper(II) species doped into zinc(II) complex adopts the zinc(II) trigonal bipyr...
77 citations
TL;DR: Three coordination polymers of copper(II) have been synthesized by the process of self-assembly using Cu(ida) [ida = iminodiacetate(2-)] as the building block and 4,4'-bipyridyl and 1,2-bis(4-pyridymethane)ethane (bpa) as linkers.
Abstract: Three coordination polymers of copper(II), viz. {[Cu(ida)(4,4‘-bipyH)]ClO4}∝ (1), {[Cu2(ida)2(μ-4,4‘-bipy)]·2H2O}∝ (2), and [Cu2(ida)2(bpa)]∝ (3) have been synthesized by the process of self-assembly using Cu(ida) [ida = iminodiacetate(2-)] as the building block and 4,4‘-bipyridyl and 1,2-bis(4-pyridyl)ethane (bpa) as linkers. Crystals of 1 are orthorhombic, of space group Pna21, with a = 13.8956(12) A, b = 16.3362(16) A, c = 7.3340(12), and Z = 4. Both compounds 2 and 3 crystallize in monoclinic space group P21/a with a = 10.1887(8) A (9.6779(10) A for 3), b = 8.0008(11) A (9.1718(10) A), c = 11.6684(9) A (12.9144(12) A), β = 98.307(11)° (102.796(18)°), and Z = 2 (2). Compound 1 has a zigzag chain structure with an extensive hydrogen-bonded network while compounds 2 and 3 are honeycomb (6,3) nets with interpenetrating structures. Variable temperature (2−300 K) magnetic study indicates the presence of weak antiferromagnetic interactions (J = 0.82 ± 0.01 cm-1) in 1 and ferromagnetic in 2 (J = −0.45 ± 0.05 ...
69 citations
TL;DR: Three new flexidentate 5-substituted salicylaldimino Schiff base ligands based on 1-(2-aminoethyl)piperazine and their nickel(II) complexes have been reported, and 2 and 3 have been structurally characterized by X-ray diffraction analysis.
Abstract: Three new flexidentate 5-substituted salicylaldimino Schiff base ligands (L1-OH-L3-OH) based on 1-(2-aminoethyl)piperazine (X=H, L1-OH; X=NO2, L2-OH; and X=Br, L3-OH) and their nickel(II) complexes (1a, 1b, 2, and 3) have been reported. The piperazinyl arm of these ligands can in principle have both boat and chair conformations that allow the ligands to bind the Ni(II) center in an ambidentate manner, forming square-planar and/or octahedral complexes. The nature of substitution in the salicylaldehyde aromatic ring and the type of associated anion in the complexes have profound influences on the coordination geometry of the isolated products. With the parent ligand L1-OH, the product obtained is either a planar red compound [Ni(L1-O)]+, isolated as tetraphenylborate salt (1a), or an octahedral green compound [Ni(L1-NH)(H2O)3](2+), isolated with sulfate anion (1b); both have been crystallographically characterized. In aqueous solution, both these planar (S=0) and octahedral (S=1) forms are in equilibrium that has been followed in the temperature range 298-338 K by 1H NMR technique using the protocol of Evans's method. The large exothermicity of the equilibrium process [Ni(L1-O)]+ + 3H2O + H+ [Ni(L1-NH)(H2O)3](2+) (DeltaH degrees=-46 +/- 0.2 kJ mol(-1) and DeltaS degrees=-133 +/- 5 J K(-1) mol(-1)) reflects formation of three new Ni-OH2 bonds in going from planar to the octahedral species. With the 5-nitro derivative ligand L2-OH, the sole product is an octahedral compound 2, isolated as a sulfate salt while with the bromo derivative ligand L3-OH, the exclusive product is a planar molecule 3 with associated tetraphenylborate anion. Both 2 and 3 have been structurally characterized by X-ray diffraction analysis.
68 citations
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01 Dec 1991
TL;DR: In this article, self-assembly is defined as the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds.
Abstract: Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.
2,591 citations
01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
1,652 citations
01 Jan 2009
TL;DR: The magnet-like behavior can be observed by slow relaxation of the magnetization below the blocking temperature as mentioned in this paper, and this assumption has formed the basis for the understanding of the origin of the anisotropic barrier.
Abstract: The magnet-like behavior can beobserved by slow relaxation of the magnetization below theblocking temperature. Since the discovery of SMMs in theearly 1990s, this assumption has formed the basis for theunderstanding of the origin of the anisotropic barrier.However, in recent years the development of novel lantha-nide-only SMMs that challenge and defy this theory pose anumber of questions:
495 citations
TL;DR: This paper presents the results of aalysis experiments conducted at the BNLMS and Nankai University with real-time measurements of the response of the H2O-O2/O2 mixture to E2O/O3 mixture.
Abstract: Kunbing Ouyang,†,‡ Wei Hao,† Wen-Xiong Zhang,*,†,§ and Zhenfeng Xi† †Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China ‡Institute of Chemistry, Chinese Academy of Sciences (CAS), Beijing 100190, China State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China
477 citations
TL;DR: A survey of radical ligand-containing single-molecule magnets can be found in this article, with a brief overview of other classes of metal-ligand radical complexes that could be exploited in the design of new single molecule magnet.
450 citations