Construction of new 1D and 2D coordination polymers generated from rigid N,N′-bis(4-pyridylmethylene)-1,5-naphthalenediamine ligand:Syntheses, crystal structures and luminescence properties

Treatment of N,N′-bis(4-pyridylmethylene)-1,5-naphthalenediamine (L) with Pb(OAc)2/KBr, Cu(acac)2, and Cu(OAc)2 afforded three new coordination polymers [Pb(μ-L)(μ-Br)2]n (1), [Cu(μ-L)(acac)2]n (2), and [Cu2(μ-L)(μ-OAc)4]n (3). These coordination polymers have been structurally characterized by single crystal X-ray diffraction. Compound 1 has a 2D sheet structure in which the lead(II) centers are bridged by both L and bromide ligands. Compound 2 adopts a 1D neutral coordination chain and consists of bis(2,4-pentanedionato) copper(II) units connected by rigid bridging L ligands. The structure of compound 3 also adopts a 1D neutral coordination chain in which two copper centers are connected through four acetate groups to form a Cu(OAc)4Cu paddle-wheel-type cage between two bridging L ligands. The FT-IR spectra, thermal behavior and photoluminescence properties of these coordination polymers have also been investigated.</p

Construction of one dimensional Co(II) and Zn( II) coordination polymers based on expanded N, N '-donor ligands

Four new 1-D coordination polymers [Zn(acac) 2(L1)] (n) (1), [Co(acac)(2)(L1)](n) (2), [Co(acac)(2)(L2)](n) (3) and [Co(acac)(2)(L3)] (n) (4) were afforded by the complexation reaction of appropriate zinc and cobalt metal salts, acetylacetone co-ligand as well as three linear electron rich and bi-functional N, N'-bipyridyl-base ligands of N, N'-bis(pyridin-4-ylmethylene) naphthalene-1,5-diamine (L1), N, N'-bis(pyridin-4-ylmethylene) phenylene-1,4-diamine (L2) and N, N'-bis(pyridin-4-ylmethylene) hydrazine (L3). The structures of these compounds were characterized by FT-IR spectroscopy, elemental analysis, X-ray powder and single crystal X-ray diffractions. X-ray crystallography analyses revealed that these compounds have 1-D linear chain structures a containing {N2O4} metal coordination environment in which the N-donor Lx (x = 1-3) bridges occupy trans positions. The acetylacetone (acac) ancillary ligands control the coordination number of the metal cation and adopt chelating binding mode on octahedral metal center. Furthermore, 1-D chains are held together with their neighboring ones by C-H...O, C-H...pi and pi-pi stacking intermolecular interactions to stabilize 2-D supramolecular networks. The two former cases 1 and 2, containing same L1 spacer ligand generate isomorphous structures. Theoretical calculations invoking electronic properties, frontier molecular orbital description and the strength of interactions between metal ion and coordinated atoms via second order perturbation energies were carried out using natural bond orbital analysis (NBO). Finally, thermal stability of compound 2-4 was examined by thermogravimetric (TGA) analysis. (C) 2017 Elsevier B.V. All rights reserved

Synthesis, Structural Characterization, and Electrochemical Studies of New Oxovanadium(V) Complexes Derived from 2-Furanoylhydrazon Derivatives

Five monooxovanadium(V) complexes [VO(L1)(OCH3)(OHCH3)] (1), [VO(L2)(OCH3)(OHCH3)] (2), [VO(L3)(OCH3)(OHCH3)] (3), [VO(L4)(OCH3)(OHCH3)] (4), and [VO(L5)(OCH3)(OHCH3)] (5) were synthesized and characterized by IR, NMR UV-Vis, and single-crystal structure analysis [H2L1=(E)-N′-((2-hydroxynaphthalen-1-yl)methylene)furan-2-carbohydrazide, H2L2=(E)-N′-(2-hydroxybenzylidene)furan-2-carbohydrazide, H2L3(E)-N′-(5-bromo-2-hydroxybenzylidene)furan-2-carbohydrazide, H2L4=(E)-N′-(2-hydroxy-5-nitrobenzylidene)furan-2-carbohydrazide, H2L5=(E)-N′-(2-hydroxy-5-iodobenzylidene)furan-2-carbohydrazide]. In all 1–3 structures the vanadium atom has a distorted octahedral coordination with the three meridional donor atoms from the Schiff base dianion (L1–3)2− and one methoxylato group occupying the sites of the equatorial plane. The oxo group and one methanol molecule occupy the apical sites. In the complexes 1, 2, and 3 the conformation of 2-furanyl oxygen atom relative to the carbohydrazide oxygen atom is s-anti, s-anti/s-syn, and s-syn at 293 K, respectively. Cyclic voltammetric experiments of the solution species 1–5 in DMSO revealed a quasi-reversible behavior

Synthesis of Depsipeptides via Isocyanide-Based Consecutive Bargellini–Passerini Multicomponent Reactions

An efficient and straightforward approach has been established for the preparation of a new class of depsipeptide structures via isocyanide-based consecutive Bargellini–Passerini multicomponent reactions. 3-Carboxamido-isobutyric acids bearing an amide bond were obtained via Bargellini multicomponent reaction from isocyanides, acetone, and chloroform in the presence of sodium hydroxide. Next, via a Passerini multicomponent-reaction strategy, a new class of depsipeptides was synthesized using the Bargellini reaction products, isocyanides, and aldehydes. The depsipeptides thus prepared have more flexible structures than their pseudopeptidic analogues

Selective ipso-Nitration of tert-Butylcalix[4]arene Tripropylether

An improved selective ipso-nitration of the tripropoxy derivative of tertbutylcalix[4]arene at the upper rim is described. The synthesized products are key intermediates for construction of molecular receptors based on calixarenes

Selective ipso-Nitration of tert-Butylcalix[4]arene Tripropylether

An improved selective ipso-nitration of the tripropoxy derivative of tertbutylcalix[4]arene at the upper rim is described. The synthesized products are key intermediates for construction of molecular receptors based on calixarenes

A series of 1-D zinc(II) coordination polymers with 3-D supramolecular networks: synthesis, structural investigation, and NBO analysis

N,N '-Bis(pyridin-4-ylmethylene)naphthalene-1,5-diamine (L) acts as a bipyridine analogue linker ligand towards {Zn-7(mu(4)-O)(2)(OAc)(10)}, {Zn-2(NCS)(2)(OAc)(2)}, and {Zn(N-3)(2)} nodes and allows construction of three new 1-D coordination polymers, the linear chain [Zn-7(mu(4)-O)(2)(OAc)(10)(L)](n) (1), [Zn(NCS)(OAc)(L)](n) (2) in ladder-type geometry and the zigzag chain [Zn(N-3)(2)(L)](n) (3). Structural characterization reveals that in 1 acetate anionic ligands connect seven Zn(II) ions through the bridging coordination modes mu(3)-eta(1),eta(2) and mu(2)-eta(1),eta(1). The resulting heptanuclear node is located on an inversion center and therefore consists of four crystallographically distinct cations; their coordination spheres correspond to distorted octahedra or tetrahedra. The Zn(II) ions in polymer 2 exhibit distorted trigonal bipyramidal {ZnN3O2} coordination; mu(2)-eta(1),eta(1) coordinated acetate and terminal thiocyanate ligands lead to inversion-symmetric [Zn-2(NCS)(2)(OAc)(2)] secondary building units (SBU), which are further linked by the N,N '-bipyridine analogue L. Terminal coordination of two anionic azide ligands and the bridging bipyridine L result in coordination polymer 3, in which the cations adopt distorted tetrahedral {ZnN4} coordination. In all crystalline solids 1-3, adjacent 1-D chains interact through pi-pi stacking and non-classical (C - H center dot center dot center dot O, C - H center dot center dot center dot pi) hydrogen bonds, leading to 3-D supramolecular architectures. Differences in their 3-D arrangement are due to variations in the anionic co-ligands, subtle conformational differences in the semi-rigid linker and the variable coordination sphere about the zinc cations. Thermogravimetric investigations indicate differences in both thermal stability and decomposition mode. Natural bond orbital (NBO) analysis provides a convenient basis for investigating the intramolecular bonding interactions and delocalization effects in these molecular systems. Finally, solids 1-3 exhibit intense luminescence at room temperature