Wen-Hong Jiang

Two pairs of Zn(II) coordination polymer enantiomers based on chiral aromatic polycarboxylate ligands: synthesis, crystal structures and properties

Two pairs of Zn-based chiral coordination polymers (CCPs), namely, [Zn((R)-cbca)·H2O], [Zn((S)-cbca)]·H2O], [Zn((R)-cna)·2H2O] and [Zn((S)-cna)·2H2O] {H2cbca = (R) or (S)-4′-(1-carboxyethoxy)-[1,1′-biphenyl]-4-carboxylic acid, H2cna = (R) or (S)-6-(1-carboxyethoxy)-2-naphthoic acid} were synthesized under hydrothermal conditions. Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction, circular dichroism (CD) spectroscopy. CCPs 1–4 crystallized in chiral space groups and the CD spectra demonstrate obvious positive or negative Cotton effects. Second-harmonic generation (SHG) measurements show that CCPs 1–4 are SHG active and the SHG efficiencies are 0.6, 0.6, 0.5 and 0.5 times as much as that of urea, respectively. CCPs 1–4 exhibit relatively high luminescence properties originating from ligand centered emission.

A pair of novel Zn(II) enantiomeric coordination polymers based on a chiral multicarboxylate ligand: synthesis, crystal structures and molecular recognition properties

A pair of Zn(II) enantiomeric coordination polymers, 1-R and 1-S, namely, [Zn4((R)-H3L)2(OH)2(H2O)2]·3H2O {H3L= (R)- or (S)-5-(1-carboxyethoxymethyl)-isophthalic acid}, were synthesized via solvothermal reactions. Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by IR spectra, elemental analyses, thermogravimetric analysis (TGA), solid-state circular dichroism (CD) and powder X-ray diffraction (PXRD). The pair of enantiomers crystallized in the same chiral space group, featuring a 3,6-c net and kgd topological type structure with a point symbol of (43)2(46·66·83). Their CD spectra exhibit obvious positive or negative Cotton effects, indicating their homochirality. 1-R and 1-S also proved to be second-harmonic generation (SHG) active. Moreover, their fluorescent selective recognition towards nitro aromatic compounds and metal cations were also investigated.

Five Co(II) coordination polymers with different counter anions based on [3,5-di(4H-1,2,4-triazol-4-yl)benzoato]− ligand: directed synthesis, structures and magnetic properties

As a continuing challenge to obtain the desired coordination polymers in the synthesis stage, the counter ions, the metal–ligand ratio and the involvement of template have great impact on their structure construction and crystal growth. In this paper, three different crystals of coordination polymers 1–3 {{[CoL(μ2-OH)]}n (1), {[CoL2(H2O)]·H2O}n (2), {[Co3L3(H2O)]·3NO3·4H2O}n (3)} {L = [3,5-di(4H-1,2,4-triazol-4-yl)benzoate]−} were obtained in one pot with HL and Co(NO3)2. By tuning the reactants ratio and employing different templates, each complex could also be synthesized separately. Single-crystal X-ray analyses show that complex 1 exhibited a two-dimensional (2D) layered gek2 net structure. Complex 2 with deprotonated [L]− has two dimensional (2D) nets structure with 3,5L66 topology. Complex 3 displays a new 5,5,6,6-connected three-dimensional (3D) topological network with a point symbol of (410·65)(45·65)2(47·63)2(48·67). When the reactant Co(NO3)2 was changed to CoCl2 or CoSO4, 4 and 5 {{[CoL(Cl)]·H2O}n (4) and {[Co2L2(SO4)(H2O)]·2H2O}n (5)} was formed with a similar structure to that of 1. Complexes 4 and 5 are two-dimensional (2D) frameworks with 4,6L26 topology. Five complexes have been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and thermogravimetry measurements. The magnetic properties of 1–5 are also investigated. The magnetic property investigation reveals that complex 1 exhibits frequency-dependent behavior.