ABSTRACT
A novel high-nuclear nanosized cluster modified by conjugated organic ligands (pyridine and imidazole), [C5NH5]8[C3H5N2]2{[C5NH5]9[H31Mo12O24Co12(PO4)23(H2O)4]}·12H2O (1), has been successfully isolated under hydrothermal conditions and structurally characterized. Compound 1 consists of 12 CoII and 12 MoV ions linked by 23 {PO4} groups, exhibiting unprecedented nanosized ship-shaped clusters. The magnetic measurements reveal that compound 1 exhibits dominant antiferromagnetic interactions. Additionally, pyridine and imidazole ligands enhance the delocalized electron effects of clusters, and the third-order nonlinear-optical response of compound 1 is excellent.
ABSTRACT
Two new monosubstituted Keggin structural polyoxometalates [H5PMo11O39Zn(C5H5N)]·(C5H5N)5·H2O (1) and [H5PW11O39Co(C5H5N)]·(C5H5N)2·(C6H8N)2·1.5CH3OH (2) have been successfully synthesized under hydrothermal conditions. Structural analysis indicates that the polyoxoanion of compound 1 is a solvent molecule-bonded zinc-monosubstituted Keggin structural cluster, [PMo11O39Zn(C5H5N)](5-), while the polyoxoanion of compound 2 is a cobalt-monosubstituted phosphotungstate polyanion bonded with one pendant pyridine molecule. Both 1 and 2 show 3D supramolecular interpenetrating structures constructed of inorganic polyanion layers and organic layers. Very interestingly, compounds 1 and 2 exhibit excellent third-order NLO properties, and the TPA cross section σ of 1 and 2 is 2571.3 GM and 2876.3 GM, respectively.
ABSTRACT
The first polyoxometalates modified by a porphyrin-resembling planar Schiff base have been successfully designed and synthesized under hydrothermal conditions. The third-order NLO responses indicated that they are excellent third-order NLO materials. Their catalytic performances are also investigated.
ABSTRACT
A total of six three-dimensional chiral coordination compounds L- and D-[LnZn(IN)3(C2H4O2)]n (Ln = Eu, Sm, and Gd; HIN = isonicotinic acid) have been successfully synthesized under hydrothermal conditions without any chiral auxiliary and characterized by IR, TG, elemental analyses, and solid-state circular dichroism spectra. The structures of 1-6 were determined by single-crystal X-ray structural analysis, which shows that L-[LnZn(IN)3(C2H4O2)]n (Ln = Eu (1), Sm (2), and Gd (3)) crystallize in space group P6522 and are levogyrate. The chiral frameworks of L-[LnZn(IN)3(C2H4O2)]n are constructed from L-helical Ln-O-Zn cluster chains, while adjacent L-type helical -[Ln-O-Zn]n- chains are connected through IN(-) ligands. D-[LnZn(IN)3(C2H4O2)]n (Ln = Eu (4), Sm (5), and Gd (6)) crystallize in space group P6122, and their chiral frameworks consist of D-helical Ln-O-Zn cluster chains. The observed second-harmonic generation efficiencies of [EuZn(IN)3(C2H4O2)]n, [SmZn(IN)3(C2H4O2)]n, and [GdZn(IN)3(C2H4O2)]n are 0.4, 0.3, and 0.3 times that of urea, respectively. We also studied luminescence spectra and luminescence lifetimes of 1 and 2. The luminescence lifetimes of 1 and 2 are 1.18 ms, and 29.6 µs, respectively.
ABSTRACT
Three novel polyoxoanion-supported compounds modified by conjugated organic ligand tris(2-benzimidazylmethyl)amine (NTB) and nickel ions, [Ni(NTB)(H2O)]2(H2P2Mo5O23)·9.25H2O (1), [Ni(H2O)(NTB)]2(PMoMo(V)O40)·4.5H2O (2) and [Ni(NTB)]2(Mo8O26)·9H2O (3), have been successfully synthesized under hydrothermal conditions at different pH values. The compounds 1-3 contain similar rigid concave surfaces composed of [Ni(NTB)](2+) cations, which connect with different clusters to form the first examples of metal-NTB-modified polyoxoanion-supported compounds. Transition metal-containing rigid concave surfaces successfully confine polyoxoanions in compounds 1-3. In the synthesis of the three compounds, the pH values play an important role in the formation of polyoxoanions and the stability of the compounds. Additionally, the third-order nonlinear optical properties (NLO) and electrochemical behaviors were also investigated.
ABSTRACT
A new vanadium sulfate, [H2N(CH3)2](19/3)(en)[V5O5(µ3-O)4(SO4)4](SO4)(2/3)[HN(CH3)2](2/3) 1, constructed from novel umbrella-like [V(V)(µ3-O)4V(IV)4O5(SO4)4(en)](5-) anions was synthesized and structurally characterized using single-crystal X-ray analysis. The magnetic and optical studies of 1 indicate that the title compound exhibits significant ZFS (zero field splitting), interesting ferrimagnetic interactions and strong two photon absorption.
ABSTRACT
Two novel organic-inorganic hybrids, Na[PMo(V)8Mo(VI)4O38(OH)2Zn4][pyim]2·1.5H2O [ε(pyim)2] (pyim = 2-(2-pyridyl)-imidazole) and [PMo(V)8Mo(VI)4O37(OH)3Zn4]2[pyim]6·4H2O [ε2(pyim)6], based on ε-Zn Keggin units {ε-PMo(V)8Mo(VI)4O(40-x)(OH)(x)Zn4}, have been successfully synthesized under hydrothermal conditions by controlling the pH values. Structural analysis indicates that the framework of ε(pyim)2 is a 1D chain constructed by monomeric ε-Zn units modified by pyim ligands, while ε2(pyim)6 is an isolated structural compound with dimeric ε-Zn units modified by pyim ligands. This is the first isolated structure of the ε-Keggin POMs system. The luminescent and electrochemical properties of ε(pyim)2 and ε2(pyim)6 were investigated. ε2(pyim)6 also shows high catalytic activity for the esterification of phosphoric acid with equimolar lauryl alcohol to monoalkyl phosphate ester (MAP).
