2,2 ',6,6 '-Tetraisopropylbenzidine-Based Sterically Encumbered Ditopic C-2-Symmetric Ligand Systems and Supramolecular Building Blocks

Starting from 2,2',6,6'-tetra-isopropylbenzidine (TBZ), a family of sterically encumbered pseudo-C-2-symmetric based ligand systems and supramolecular building blocks have been synthesized. Schiff base scaffolds (iPr)(4)(C6H2)(2)(NAr')(2) (1-9) (Ar' = -CH(C6H4)(OH) (1); -CH(C6H2)(Me)(2)(OH) (2); -CH(C6H2)(tBu)(2)(OH) (3); -CH(C6H2)(tBu)(Br)(OH) (4); -CH(C6H3)(OMe)(OH) (5); -CH(C6H4)(4-OH) (6); -CH(2-Py) (7); -CH(3-Py) (8); -CH(4-Py) (9)), (iPr)(4)(C6H2)(2)(NH(C)(CH)(CO)Me-2)(2) (10), (NH2(iPr)(4)(C6H2)(2))(2) (N(C)(CH)(C)N)Me-2 (11), (NH2(iPr)(4)(C6H2)(2)N(CO)(C6H4)(CH2) (12) and (iPr)(4)(C6H2)(2)(N(CO)(C6H4)(CH2))(2) (13) have been assembled through condensation of TBZ with the corresponding formyl compounds. TBZ was also further employed to synthesize two carboxylic acid derivatives, ((iPr)(4)(C6H2)(2)(N(CH2COOH)(2))(2)) (14) and ((iPr)(4)(C6H2)(2)(COOH)(2)) (16), both potential connector ligands for MOFs. To explore main group chemistry aspects of TBZ, bis- and tetra-trimethylsilyl derivatives (iPr)(4)(C6H2)(2)(R)(2) (R= (-NH(SiMe3))(2) (17) and (-N(SiMe3)(2))(2) (18)) have been synthesized. The bis-dichlorophosphine derivative ((iPr)(4)(C6H2)(2)(N(PCl2)(2))(2)) (19), a compound with promising chemistry for P-based covalent organic frameworks, has been synthesized by a solvent-free reaction of TBZ with excess PCl3

Zinc Dialkylhydroxybenzoates with Unusual Structures: First Example of a Discrete Three-Blade Paddle-Wheel and a Solvent Engulfed Coordination Polymer

Sterically encumbered 4-hydroxy-3,5-diisopropylbenzoic acid (H(2)diphba), bearing a carboxylic acid, a phenol and two isopropyl substituents, has been investigated for the first time as a ligand and supramolecular synthon to isolate eight Zn(II) complexes, [Zn-2(Hdiphba)(3)(OAc)(L)] (L = DMF(1) or pyz (2)), [Zn (Hdiphba)(2)(2,2'-bpy)] (3), [Zn(Hdiphba)(2)(1,10-phen)] (4), [Zn (Hdiphba)(2)(pz)(2)] (5) and [Zn-2(Hdiphba)(2)(mu(2)-dmpz)(2)(Hdmpz)(2)] (6), [Zn(Hdiphba)(2)(4,4'-bpy)](n).4nCH(3)OH (7.4nCH(3)OH), [Zn-2(Hdiphba)(4) (4,4'-azobpy)(H2O)(2)] (8.H(2)diphba), which have been structurally characterized. Compounds 1 and 2 are rare examples of symmetrically bridged triple-blade molecular tricarboxylate paddle-wheels which self-assemble into hexameric units. Compounds 3, 4 and 5 are mononuclear complexes, bearing two exposed phenolic -OH groups self-assembled into 2-D arrays via both hydrogen bonding and p-p stacking interactions. Compound 6 is a rare example of bis-pyrazolate bridged dinuclear Zn(II) complex with two pyrazole N-H and two phenolic -OH groups on the molecular periphery to form hydrogen bonds. The use of 4,4'-bpy leading to a zig-zag 1-D polymer 7 composed of [Zn(Hdiphba) 2(4,4'-bpy)] n chains, positioned 10.77 angstrom apart. The 1-D channels of 7 are occupied by hydrogen bonded methanol with a rare (CH3OH)(4) cluster as the repeating unit. Compound 8 is a discrete bimetallic complex, isolated with a free H(2)diphba ligand. The photoluminescence spectra of 1-8 exhibit ligand centered emission at around 325 nm

Dependence of the SBU length on the size of metal ions in alkaline earth MOFs derived from a flexible C-3-symmetric tricarboxylic acid

Four new alkaline-earth metal-based metal-organic frameworks, [Mg-4(TCMTB)(2)(OAc)(2)(DMA)(2)(H2O)(3)](n) (Mg-TCMTB), {[Ca-4(TCMTB)(2)(OH)(DMF)(2)(H2O)(5)] center dot Cl}(n) (Ca-TCMTB), [Sr-4(TCMTB)(2)(OH)(OAc)(DMA)(6)(H2O)](n) (Sr-TCMTB) and [Ba-9(TCMTB)(4)(NO3)(6)(DMA)(14)](n) (Ba-TCMTB) (H3TCMTB = 2,4,6-tris[(4'-carboxyphenoxy)-methyl]- 1,3,5-trimethylbenzene), have been synthesized and structurally characterized. Structural analysis of the MOFs reveals the presence of diverse structures and topologies in these systems due to the conformational flexibility and multiple coordination sites in H3TCMTB. Coordination polymers Mg-TCMTB, Ca-TCMTB and Ba-TCMTB MOFs are three-dimensional frameworks exhibiting 2-fold interpenetration and one-dimensional hexagonal channels, while Sr-TCMTB is a 2-fold interpenetrated layered MOF. The 2D layers in Sr-TCMTB are interconnected through H-O center dot center dot center dot H hydrogen bonds. Increasing ionic radii and coordination number on moving down the group results in the formation of bi-, tetra-and nona-nuclear M-O-M connected inorganic building units. Owing to its smaller size and lower coordination number, framework Mg-TCMTB gives rise to a moderate surface area of 33.0 m(2) g(-1) (SA(BET)) and 93.8 m(2) g(-1) (SA(Lang)) which is the highest observed among all the four MOFs. Emission studies of the new MOFs reveal the presence of strong photoluminescence at 380 nm

Synthesis, structure, redox behavior, catalytic activity and DFT study of a new family of ruthenium(III)1-(arylazo)naphtholate complexes

Treatment of [RuCl2(DMSO)(4)] with 1-(arylazo)naphthol ligands in benzene under reflux afford the air stable new ruthenium(III) complexes with general composition [Ru(L-R)(3)] (L = bidentate O, N donor; R = H, CH3, OCH3, Br, NO2) in good yield. The 1-(arylazo)naphthol ligands behave as tris-bidentate 0, N donors via naphtholic proton and azo nitrogen. The molecular and electronic structure of the complexes have been established by elemental analysis and spectral (FT-IR, UV-vis & EPR) methods. DFT calculations were also carried out on the complexes 1 and 3 along with X-ray crystallized geometry of complex 5. These complexes in dichloromethane solution show intense ligand-to-metal charge transfer (LMCT) transitions in the visible region. The absorption and g-tensor value of these complexes (1, 3 & 5) were also computed and compared along with the available experimental results. The redox behavior of the complexes has been investigated by cyclic voltammetry and the potentials are observed with respect to the electronic nature of substituents (R) in the 1-(arylazo)naphthol ligands. These complexes have shown great promise as catalysts for the conversion of aldehydes to primary amides in good yield. (C) 2016 Elsevier B.V. All rights reserved

Alkyl-Chain-Separated Triphenybenzene - Carbazole Conjugates and their Derived Polymers: Candidates for Sensory, Electrical and Optical Materials

Four new triphenylbenzene based carbazoles (THPBCz4, THPBCz6, THPBCz8 and THPBCz10) and polycarbazoles (polyTHPBCz4, polyTHPBCz6, polyTHPBCz8 and polyTHPBCz10), have been synthesized. Photoluminescence spectra of the monomers in dichloromethane exhibit two intense bands at 353 and 369 nm. Two additional bands (410 and 435 nm) are also observed due to intermolecular interactions. These bands are more intense in the case of thin films, indicating stronger pp stacking interactions in the solid state. Due to the extended p-conjugation, the polycarbazoles display two main emission bands (495 and 520 nm) which are red shifted as compared to the monocarbazoles. Due to the presence of emissive platforms such as triarylbenzene and carbazole, both monomers and polymers, function as efficient sensors for the detection of polynitroaromatic analytes (PA, DNT, rho-DNB and m-DNB). The electrochemically polymerized carbazole derivatives showed maximum capacitance of 41 F/g for polyTHPBCz6. The SCLC measurement reveals a maximum mobility of 6 x 10(-6) cm(2)/Vs for polyTHPBCz4 that showed better packing due to flexible alkyl chains that connect the conjugated moieties