A trinuclear complex [(CuL)2Tb(H2O)(NO 3)3]·MeOH·H2O (1) is synthesized by using a metalloligand [CuL] (H2L = N,N′-bis(salicylidene)-1, 3-propanediamine or salpn). This complex is used as a new 3d-4f metallatecton for stepwise supramolecular oligomerization along with a simple diimine linker, 4,4′-bipyridine (bpy). A ratio of metallatecton/linker = 2:1 is conducive for the formation of a dimer [{(CuL)2Tb(H2O)(NO 3)3}2bpy]·2MeOH·4H2O (2), whereas a higher proportion of linker at a ratio of 1:1 gives rise to a zigzag one-dimensional coordination polymer {[(CuL)2Tb(NO 3)3bpy]·MeOH·2H2O} ∞ (3). The inherent conformational flexibility of the trinuclear (CuL)2Tb node which is folded (cisoid) for 1 and 2 (asymmetric TbO9 tricapped trigonal prism) and unfolded (transoid) for 3 (a C2-symmetric TbO10 tetradecahedron) seems to stabilize the crystal packing of these coordination-driven self-assemblies. The rapidly saturated magnetization at 1.8 K for 1 (11 μB) and 2 (22 μB) clearly indicates the presence of Tb-Cu ferromagnetic coupling through the phenoxido bridges of the Cu(μ1,1-O) 2Tb(μ1,1-O)2Cu cores. A slow saturation behavior has been found for 3 (9.5 μB). Both in-phase and out-of-phase ac magnetic measurements of 1 under an applied dc magnetic field reveal temperature dependence of the susceptibility at different frequencies below 5 K, characteristic of single molecule magnets (SMMs), which is conserved in 2 and 3 signifying oligo- and polymeric aggregates of SMMs. © 2014 American Chemical Society.

ASHUTOSH GHOSH

Chemistry

S GHOSH

Y IDA

T ISHIDA

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Crystal Growth and Design

Four new tri-nuclear hetero-metallic copper(II)-cadmium(II) complexes [(CuL)2CdCl2] (1), [(CuL)2CdBr2] (2), [(CuL)2CdI2] (3) and [(CuL)2Cd(NO3)2] (4) have been synthesized using [CuL] as ‘‘ligand complex’’ (where H2L = N,N′-bis(2-hydroxynaphthyl-methylidene)-1,3-propanediamine) and characterized by elemental analysis, IR, UV–Vis spectroscopy and single crystal X-ray diffraction studies. Crystal structure analyses reveal that all four complexes consist of a tri-nuclear moiety in which two square-pyramidal [CuL] units are bonded to a central Cd(II) ion through double phenoxido bridges. The Cd(II) is in a six-coordinate octahedral environment being bonded additionally to two mutually trans chloride (in 1), bromide (in 2), iodide (in 3) and oxygen atoms of nitrate (in 4) ions. Presence of several non-covalent interactions (i.e. π···π, C[sbnd]H···O and Cu···Cu interactions) has been observed in the crystal packing of all the four molecules that assist the formation of 1D supramolecular assemblies in the solid state. The interactions were investigated by means of high level DFT calculations (PBE0-D3/def2-TZVP) with the help of TURBOMOLE 7.0 program, characterized using Bader's theory of “atoms-in-molecules” (AIM) and rationalized using molecular electrostatic potential (MEP) surface calculations. © 2019 Elsevier B.V.

Inorganica Chimica Acta

Tri-nuclear copper-cadmium complexes of a N2O2-donor ligand with the variation of counter anions: Structural elucidation and theoretical study on inter-molecular interactions

Reactions of Zn(II) ion with the ligand H2L (H2L = N,N'-dimethyl-N,N'-bis(2-hydroxy-3-methoxy-5-methylbenzyl)ethylenediamine) in the presence of bridging coligands, chloride, thiocyanate/acetate, or azide/acetate yielded three new dinuclear complexes, [Zn2LCl2(H2O)] (1), [Zn2L(SCN)(2)(H2O)].H2O (2), and [Zn2L(N-3)(CH3CO2)] (3), whereas Cd(II) ion formed three new tetranuclear complexes, [Cd4L2Cl4].H2O (4), [Cd4L2(SCN)(2)(CH3CO2)(2)].2H(2)O (5), and [Cd4L2(N-3)(2)(CH3CO2)(2)].3H(2)O (6) with the same ligand and coligands. The Zn(II) ions are penta-coordinated in all of its complexes 13 except one zinc center in complex 3, which is distorted tetrahedral. All four Cd(II) centers in each of its complexes 4 and 5 possess hexa-coordinated distorted octahedral geometry. In complex 6, two Cd(II) centers are hexa-coordinated, and the other two are hepta-coordinated. The deprotonated ligand (L-2) is hexa-/hepta-dentate in the Zn(II) complexes, 13 but octa-dentate in the CdII complexes 46. The differences in nuclearity and in the coordination modes of the ligands in the resulting complexes have been explained considering the preference for different coordination numbers of these two metal ions. H2L exhibited highly specific, sensitive, and selective turn-on fluorescence sensing properties for the Zn2+ ion. The mechanism of fluorescence enhancement, host guest binding stoichiometry, and binding constant has also been calculated. The detection limit of Zn2+ ion is 7.69 nM, with the binding constant K = 1.508 x 10(10) M-2. The produced Zn(II) complexes sense nitroaromatic explosives in solution via a turn-off florescence response. The solution phase sensing mechanism has been studied thoroughly. Remarkably, the limit of detection of picric acid at the ppt level (912, 910, and 896 ppt for complexes 1, 2, and 3 respectively) having a strong quenching constant (K-SV) is 8.063 x 10(4), 7.987 x 10(4), and 8.51 x 10(4) M-1 for complex 1, 2, and 3 respectively.

Modulation of Nuclearity by Zn(II) and Cd(II) in Their Complexes with a Polytopic Mannich Base Ligand: A Turn-On Luminescence Sensor for Zn(II) and Detection of Nitroaromatic Explosives by Zn(II) Complexes

Four new one-dimensional coordination polymers {[(CuL)2Cd(p-BDC)]·H2O}n (1), {[(CuL)2Mn(p-BDC)]·H2O}n (2), {[(CuL)2Cd(m-BDC)][(CuL)2]}n (3), and {[(CuL)2Mn(m-BDC)][(CuL)2]}n (4), where H2L = N,N′-bis(α-methylsalicylidene)-1,3-propanediamine, have been synthesized using bimetallic trinuclear nodes, [(CuL)2M] (where M is MnII/CdII and p-BDC and m-BDC are 1,4- and 1,3-benzenedicarboxylate, respectively). Crystal structures show that all four complexes form 1D chains in which the heterometallic linear trinuclear nodes are connected by syn-syn bridging dicarboxylate linkers. However, in 1 and 2 the nodes which are connected by linear p-BDC are parallel to each other whereas in 3 and 4 the nodes are inclined towards each other to be connected by the angular m-BDC linker. Moreover, complexes 3 and 4 are co-crystallized with dimeric CuII units which are accommodated in the cavities between polymeric chains. This difference in the solid-state crystal packing is explained theoretically by DFT calculations of complexes 1 and 3 considering the positional isomeric effect of dicarboxylate linkers. Variable temperature magnetic susceptibility measurements of complexes 2 and 4 indicate antiferromagnetic interactions between the CuII and MnII centers with J = -13.08 and -12.11 cm-1 for 2 and 4, respectively. © 2018 The Royal Society of Chemistry.

CrystEngComm

Joining of trinuclear (CuL) 2 M (M = Mn II and Cd II ) nodes by 1,3- and 1,4-benzenedicarboxylate linkers: Positional isomeric effect on co-crystallization

A new series of heterometallic trinuclear Cu2Ln complexes [lanthanide ions Ln = Gd (1), Tb (2), Dy (3), Ho (4) and Er (5)] has been synthesized using a Cu(ii)-metalloligand derived from a N2O2 donor unsymmetrical Schiff base, H2L (where H2L = N-α-methylsalicylidene-N′-salicylidene-1,3-propanediamine), and structurally characterized. Among these complexes, [(CuL)2Gd(NO3)3(CH3CN)2] (1), [(CuL)2Tb(NO3)3(CH3CN)2] (2) and [(CuL)2Dy(NO3)3(CH3CN)2] (3) are isomorphic and isostructural. In these complexes two metalloligands coordinate to the central Ln(iii) (Ln = Gd, Tb and Dy respectively) ion in a transoid fashion via μ2-phenoxido oxygen atoms. The Ln(iii) ions are deca-coordinated with a distorted tetradecahedron geometry. The two terminal Cu(ii) ions of the complexes possess a hexa-coordinated distorted octahedral geometry. In contrast, in complexes [(CuL)2Ho(NO3)3(CH3CN)], (4) and [(CuL)2Er(NO3)3(CH3CN)]·0.5(CH3CN) (5), the two metalloligands coordinated to the Ln(iii) ions in a cisoid fashion. The Ho(iii) ion in 4 is nona-coordinated with a distorted tricapped trigonal prismatic geometry and the Er(iii) ion in 5 is octa-coordinated with a distorted square antiprismatic geometry. The two terminal Cu(ii) ions in complexes 4 and 5 are penta-coordinated with a distorted square-pyramidal geometry. The dc magnetic susceptibilities and field dependent magnetization measurement of complex 1 reveal the occurrence of ferromagnetic interactions between Cu(ii) and Gd(iii) ions as well as intermolecular antiferromagnetic interactions. Both complexes 2 and 3 show ferromagnetic interactions between Cu(ii) and Ln(iii) ions. The ac magnetic susceptibilities of all the complexes were also recorded and it was found that only complexes 2 and 3 exhibit slow relaxation of magnetization reorientation below 10 K at 2000 Oe applied dc field, this being characteristic of single molecule magnets. © 2017 The Royal Society of Chemistry.

Dalton Transactions

Structural variations in (CuL)2Ln complexes of a series of lanthanide ions with a salen-type unsymmetrical Schiff base(H2L): Dy and Tb derivatives as potential single-molecule magnets

Four new trinuclear linear homo-metallic complexes [(CuLR)(2)Cu(NCS)(2)]center dot(CH3)(2)CO (1), [(CuLR)(2)Cu(NO3)(2)] (2), [(NiLR)(2)Ni(NCS)(2)center dot(CH3CN)(2)] (3), [(NiLR)(2)Ni(NO3)(2)center dot((CH3)(2)CO)(2)] (4) have been synthesized using [CuLR] and [NiLR] as metalloligands (where H2LR N,N'-bis(2-hydroxybenzyl)-1,3-propanediamine) along with polyatomic anions, thiocyanato or nitrato. All four complexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD, DFT and magnetic study. In all complexes, two units of metalloligands, [CuLR] or [NiLR] coordinate to the central copper or nickel atom through double phenoxido bridges forming a linear trinuclear structure. In the structures of 1 and 3, the N -bonded thiocyanato ion coordinates to the terminal metal centers of the trinuclear unit to complete the distorted square pyramidal and octahedral geometry, respectively; the central metal ions remain square planar in both structures. The coordination of thiocyanato to terminal Cu(II) and Ni(II) instead of central metal ion is unusual compared to the complexes of analogous unreduced species. On the other hand, complexes 2 and 4 possess usual structures in which the anionic coligand, nitrato bridges the central and terminal metal centers. The geometries of central metal ions are octahedral in both structures and those of terminal metal ions are square pyramidal in 2 and octahedral in 4. DFT calculations show that experimentally obtained structure 1 is the most stable compared with the possible other hypothetical isomers but complex 3 is energetically slightly disfavored and possibly packing forces stabilize it in the solid state. Variable temperature magnetic susceptibility measurements show the presence of strong antiferromagnetic exchange interactions mediated through the phenoxido bridges with J values of -328.9, -474.8, and -11.13 cm(-1) for 1, 2, and 4, respectively. In complex 3, the central Ni(II) ion is diamagnetic, in agreement with its square planar geometry; however small antiferromagnetic interaction is found between the terminal Ni(II) ions with a J value equal to -5.36 cm(-1). (C) 2016 Elsevier Ltd. All rights reserved.

Polyhedron

Unusual site selection of NCS- in trinuclear complexes of Cu(II) and Ni(II) with a reduced N2O2 donor Schiff base: Structural, theoretical and magnetic studies

Three new heterometallic copper(II)-cobalt(II) complexes [(CuL 2)2Co{dca}2]·H2O(1), [(CuL1)2Co{dca}2]n (2a), and [(CuL1)2Co{dca}2]n (2b) [dca - = dicyanamide = N(CN)2-] have been synthesized by reacting the "metallo-ligand" [CuL1] or [CuL2] with cobalt(II) perchlorate and sodium dicyanamide in methanol-water medium (where H2L1 = N,N′- bis(salicylidene)-1,3-propanediamine and H2L2 = N,N′-bis(α-methylsalicylidene)-1,3-propanediamine). The three complexes have been structurally and magnetically characterized. Complex 1 is a discrete trinuclear species in which two metallo-ligands coordinate to a cobalt(II) ion through the phenoxido oxygen atoms along with two terminally coordinated dicyanamide ions. On the other hand, complexes 2a and 2b are one of the very scarce examples of supramolecular isomers since they present the same [(CuL1)2Co{dca}2] trinuclear units (very similar to the trinuclear core in 1) and differ only in their superstructures. Thus, although each Cu2Co trimer in 2a and 2b is connected to four other Cu2Co trimers through four μ1,5-dca- bridges, 2a presents a square two-dimensional structure (each Cu2Co trimer is connected to four in-plane Cu2Co trimers); whereas, 2b shows a triangular three-dimensional lattice (each Cu2Co trimer is connected to three in-plane and one out-of-plane trimers). Variable-temperature magnetic susceptibility measurements show the presence of moderate antiferromagnetic exchange interactions (ferrimagnetic) in all the cases mediated through the double phenoxido bridges that have been fitted with an anisotropic model including spin-orbit coupling in the central Co(II) ion. © 2014 American Chemical Society.

Inorganic Chemistry

Supramolecular 2D/3D isomerism in a compound containing heterometallic Cu II 2 Co II nodes and dicyanamide bridges

Linker stoichiometry-controlled stepwise supramolecular growth of a flexible Cu2Tb single molecule magnet from monomer to dimer to one-dimensional Chain

Three new hetero-metallic Cu(ii)-Zn(ii) compounds [(CuL 1 ) 2 Zn(N(CN) 2 ) 2 ] (1), 2 ∞ [(CuL 2 ) 2 Zn(μ 1,5 -N(CN) 2 ) 2 ] n (2A) and 3 ∞ [(CuL 2 ) 2 Zn(μ 1,5 -N(CN) 2 ) 2 ] n (2B) have been synthesized by reacting a [CuL 1 ] or [CuL 2 ] "metalloligand" (where H 2 L 1 = N,N′-bis(α-methylsalicylidene)-1,3- propanediamine and H 2 L 2 = N,N′-bis(salicylidene)-1, 3-propanediamine) with zinc perchlorate hexahydrate and sodium dicyanamide, using various molar ratios of the reactants. All three products have been characterized by IR and UV-Vis spectroscopies, ESI-MS, elemental, powder and single crystal X-ray diffraction analyses. Complex 1 is a discrete 0D trinuclear species in which two "metalloligands" coordinate to a zinc(ii) ion through phenoxido oxygen atoms along with two terminal dicyanamido ligands. In contrast, products 2A and 2B are 2D and 3D coordination polymers, respectively, which bear a common [(CuL 2 ) 2 Zn(N(CN) 2 ) 2 ] trinuclear unit wherein, however, dicyanamido moieties adopt a μ l,5 -bridging coordination mode. The coordination networks have been formed via the linkage, in different manners, of the trinuclear nodes [(CuL 2 ) 2 Zn] 2+ through Zn and Cu centres with the help of divergent dicyanamido spacers. These two isomeric coordination polymers represent a rare example of "genuine supramolecular isomerism". The coordination networks in 2A and 2B have been classified from the topological viewpoint, revealing a binodal 3,4-connected underlying net with the 3,4L21 topology in 2A and a uninodal 4-connected underlying net with the qtz (quartz, 4/6/h1) topology in 2B. Electronic spectra and ESI mass spectra show that all three complexes lose their solid state identity in solution. This journal is © the Partner Organisations 2014.

Discrete 0D and polymeric 2D and 3D derivatives assembled from [(CuL) 2 Zn] 2+ and dicyanamide blocks (H 2 L = salen type Schiff bases): Genuine supramolecular isomers with distinct topologies

Three new trinuclear nickel (II) complexes with the general composition [Ni3L3(OH)(X)](ClO4) have been prepared in which X=Cl- (1), OCN- (2), or N3- (3) and HL is the tridentate N,N,O donor Schiff base ligand 2-[(3- dimethylaminopropylimino)methyl]phenol. Single-crystal structural analyses revealed that all three complexes have a similar Ni3 core motif with three different types of bridging, namely phenoxido (μ2 and μ3), hydroxido (μ3), and μ2-Cl (1), μ1,1-NCO (2), or μ1,1-N3 (3). The nickel(II) ions adopt a compressed octahedron geometry. Single-crystal magnetization measurements on complex 1 revealed that the pseudo-three-fold axis of Ni3 corresponds to a magnetic easy axis, being consistent with the magnetic anisotropy expected from the coordination structure of each nickel ion. Temperature-dependent magnetic measurements indicated ferromagnetic coupling leading to an S=3 ground state with 2J/k=17, 17, and 28 K for 1, 2, and 3, respectively, with the nickel atoms in an approximate equilateral triangle. The high-frequency EPR spectra in combination with spin Hamiltonian simulations that include zero-field splitting parameters DNi/k=-5, -4, and -4 K for 1, 2, and 3, respectively, reproduced the EPR spectra well after a anisotropic exchange term was introduced. Anisotropic exchange was identified as Di,j/k=-0.9, -0.8, and -0.8 K for 1, 2, and 3, respectively, whereas no evidence of single-ion rhombic anisotropy was observed spectroscopically. Slow relaxation of the magnetization at low temperatures is evident from the frequency-dependence of the out-of-phase ac susceptibilities. Pulsed-field magnetization recorded at 0.5 K shows clear steps in the hysteresis loop at 0.5-1 T, which has been assigned to quantum tunneling, and is characteristic of single-molecule magnets. Nickel(II) magnets: A new family of trinuclear Ni II complexes with phenoxido (μ2 and μ3), hydroxido (μ3), and μ2-Cl, μ1,1-NCO, or μ1,1-N3 bridges have been prepared that form face-sharing coordination polyhedra (see figure). The three complexes exhibit a dominant ferromagnetic exchange coupling with sizable uniaxial anisotropy. The slow magnetization relaxation, the hysteresis of the pulsed-field magnetization, a magnetic easy axis, and the high-frequency EPR spectra show that these complexes constitute a new class of single-molecule magnets. Copyright © 2013 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim.

Chemistry - A European Journal

A new family of trinuclear Nickel(II) complexes as single-molecule magnets

Two new polynuclear complexes of Cu(II), [(CuL 1 )Cu(N 3 C 2 ) 2 ] n (1) and [(CuL 2 ) 2 Cu(N 3 C 2 ) 2 ] ·H 2 O (2), have been synthesized by reacting the "ligand complexes", [CuL 1 ] and [CuL 2 ] respectively with copper perchlorate and sodium dicyanamide (NaN 3 C 2 ) in ethanol-water, where the di-Schiff base ligands H 2 L 1 = N,N′-bis(salicylidene)-1,3-propanediamine and H 2 L 2 = N,N′-bis(α-methylsalicylidene)-1,3-propanediamine. Structural analysis shows that complex 1 is a 2D polymer formed by linking the dinuclear units through a μ 1,5 -dicyanamido bridge. It contains alternating helical chains of P and M types. Complex 2 is a discrete bent trinuclear species where phenoxido groups of two terminal "ligand complexes" coordinate to a central Cu(II) along with terminally coordinated dicyanamido anions. Both complexes exhibit irreversible reductive Cu(II)/Cu(I) and quasi-reversible oxidative Cu(II)/Cu(III) responses in cyclic voltammetry. The electrochemically generated Cu(I) species for both complexes are unstable and undergo disproportionation to Cu 0 and Cu 2+ . © 2012 Elsevier Ltd. All rights reserved.

Journal	Data powered by TypesetCrystal Growth and Design
Publisher	Data powered by TypesetAmerican Chemical Society
ISSN	1528-7483
Open Access	No