RhB-Embedded Mn-MOF with Cyclotriphosphazene Skeleton as Dual-Emission Sensor for Putrescine as well as Smart Fluorescent Response of Aromatic Diamines and Nitrophenol.

Luminescent metal-organic framework composites with multiple luminescence emissions have been efficient sensing platforms. Herein, a fluorescent sensor (RhB@1-0.4) with dual-emission fluorescence properties was prepared by introducing rhodamine B (RhB) into the framework of complex 1, [Mn2.5(HCPCP)(H2O)4]·(CH3CN)0.5 [HCPCP = hexa-(4-carboxyl-phenoxy)-cyclotriphosphazene and CH3CN = acetonitrile), which is a novel crystalline two-dimensional (2D) coordinated organic framework material. It is a highly desirable material, realizing a ratiometric fluorescence response to putrescine with a high signal-to-noise ratio, and the detection limit can be as low as 6.8 µM. In addition, RhB@1-0.4 exhibited a better fluorescent sensing performance for aromatic diamines and nitrophenols compared with that of complex 1. It is a potential functionalized MOF material for the application of multichannel fluorescence sensing.

A Highly Stable 3D Luminescent Indium-Polycarboxylic Framework for the Turn-off Detection of UO22+, Ru3+, and Biomolecule Thiamines.

Hydrothermal reaction of the multidentate organic ligand (H6TTHA) with indium chloride (InCl3) produced a highly stable 3D luminescent indium-organic framework [In2(OH)2(H2TTHA)(H2O)2]n (1). Complex 1 exhibits remarkable luminescent properties, especially the multifunction sensitivity and selectivity for detecting Ru3+, UO22+; as well as small biomolecules thiamines (TPP, TMP, and TCl) based on a "turn-off" manner. In particular, the pyrophosphate groups of TPP and the phosphate groups of TMP could further affect the quenching rate, leading to different luminescent responds. In addition, we also discussed and proved the luminescence quenching mechanism in detail through comparative test and PXRD characterization. Therefore, complex 1 could be used as a kind of excellent luminescence sensor to detect Ru3+, UO22+, and thiamines (TPP, TMP, and TCl).

Syntheses, crystal structures and photophysical properties of Ag(I) coordination complexes.

Three Ag(I) coordination complexes, [Ag(pyzca)]n (1) (Hpyzca=pyrazine-2-carboxylic acid), Ag[(HNA)(NA)(H2O)4] (2) (HNA=nicotinic acid) and [Ag1Ag2-(2,3-pydc)]n (3) (H2pydc=pyridine-2, 3-dicarboxylic acid) have been synthesized by the hydrothermal method. Their structures are determined by single-crystal X-ray diffractometer. Complex 1 possesses the 3D infinite structure. Complex 2 is a mononuclear coordination complex and exhibits one 3D infinite network by a large number of hydrogen bonds. In complex 3, two crystallographic independent Ag(I) ions exist, i.e., Ag1 is three-coordinate and Ag2 is two-coordinate, forming the 2D layer structure. At room temperature in the solid state, the IR, FP and UV-Vis spectra of all complexes were measured and investigated in detail. The emission and absorption spectra of the three complexes and their corresponding ligands are compared and analyzed.

A series of Ti(IV)/Ti(III) coordination polymers: structures and surface photoelectric properties.

Three titanium coordination polymers, {[Ti(SO(4))(2)(H(2)O)]·0.5bipy·2H(2)O}(n)1, {[Ti1(SO(4))(2)(H(2)O)]·[Ti2(SO(4))(2)(H(2)O)]·bipy·5H(2)O}(n)2 and [Ti(tea)](n)3 (bipy=4,4'-bipyridine, H(3)tea=triethanolamine) were synthesized and characterized by IR, UV-Vis absorption spectra, TG analysis, X-ray single crystal diffraction and surface photovoltage spectroscopy (SPS). The surface photoelectric properties of titanium coordination polymers were discussed emphatically by the SPS. The results of single crystal diffraction indicate that polymers 1 and 2 possess 1D infinite structure bridged by SO(4)(2-) groups and coordinated water molecules and further connected into supramolecular structures by hydrogen bonds. Polymer 3 possesses 2D infinite structure bridged by weak sub-coordinated Ti-O bonds. The results of SPS show that there are obvious photovoltage responses in the range of 300-500 nm, which indicates that they possess photoelectric conversion ability. The SPS of three titanium polymers were analyzed comparatively. It is found that the valence of central metal ions, coordination micro-environment and kinds of coordination atoms influence the results of the SPS. The SPS is associated with UV-Vis absorption spectra.

Syntheses, structures and photophysical properties of tetranuclear Cd-Ln coordination complexes.

Four novel hetero-tetranuclear d-f coordination complexes, [Ln2Cd2(p-toluylate)10(phen)2] (Nd, 1; Pr, 2; Sm, 3) and [Ho2Cd2(p-chloro-benzoate)10(phen)2](4) (phen = 1, 10-phenanthroline), are synthesized by the hydrothermal method, and their structures are studied by single-crystal X-ray diffraction. Structures 1-3 are isomorphous and structure 4 has a similar molecular structure. In the near-infrared (NIR) region or in the visible region, complexes 1-4 show the characteristic emission bands of Ln(III) ions, which are attributed to the sensitization from the ligands and d-block (cadmium-ligand section) to f-block (lanthanide-ligand section). Moreover, in the Cd-Ln complexes, the CdLn separation is very close, so the d-orbital of the Cd(II) ion and the f-orbital of the Ln(III) ion may influence each other, which probably cause the intra-levels to be adjusted. This can have a significant effect on the emission bands in the NIR region, hence the corresponding emission bands of complexes 1, 2 and 4 exhibit shift or splitting compared with isolated Ln(III) ions. At the same time in the UV-Vis-NIR absorption spectra of the complexes, the corresponding absorption bands also show shift or splitting. The shift or splitting of bands in the NIR emission spectra and in the absorption spectra can evidence each other.

[Crystal structures and luminescence property of d10 transition metal complexes].

Five Zn( [II)) and Cd(II) coordination complexes, [Zn(NA)2 (H2O)4](1), [Zn(INA)2 (H2O)4](2), [Zn(2,2'-bi-py)2 (SCN)2](3), [Cd(INA)2 (H2O)4](4) and [Cd(phen)2(NO3)](5) (HNA=nicotinic acid, HINA=isonicotinic acid, 2, 2'-bipy=2,2'-bipyridine, phen=1,10-phenanthroline), were synthesized through constant temperature magnetic stirrer or hydrothermal method, and their single-crystal structures were determined by X-ray diffraction. The authors measured the IR, UV-Vis-NIR and fluorescence spectra of the complexes and analyzed their photophysical properties. At room temperature in the solid state the five complexes can show strong fluorescence, i.e., lamdamax(em)=362 nm (lamda(ex)=330 nm), (1); lamdamax(em)=424 nm (lamda(ex)=330 nm), (2); lamdamax(em)=442 nm (lamda(ex)=380 nm), (3); lamdamax(em)=424 nm (lamda(ex)=330 nm), (4); lamda(em max)=456 nm (lamda(ex)=360 nm), (5), and complex (5) can emit phosphorescence upon excitation at 360 nm (lamdamax (pl)=546 nm, tau=10 ms). But the organic ligands are different, which lead to the luminescence property of complexes originating from different charge transfer. Compared with the relevant ligands (lamdamax (em)=380 nm, HNA; lamda(em max)=541 nm, 2,2'-bipy), the fluorescence emissions of complex (1) and (3) show a blue-shift which mainly comes from the ILCT (intraligand charge transfer) and at the same time exists L-->M(4S) transfer. The emissions of complex (2) and (4) come from LMCT (ligand-to-metal charge transfer) and show red-shift compared to that of free ligand (lamdamax(em)=337 nm, HINA). For complex (5), the appearance and position of its emission are different from those of the ligand (lamdamax(em)=381 nm, phen), which is attributed to LLCT (ligand-to-ligand charge transfer) and LMCT.