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A ZnII-based coordination polymer was synthesized by a mixed-ligand strategy, and it could be viewed as the first bifunctional fluorescent sensor with good stability for acac and l-His via a fluorescence red shift and enhancement.

Gd(iii)-based molecular magnetorefrigerants are reviewed and discussed in detail, with an emphasis on the synthetic strategy towards good stability and large magnetocaloric effect.

A stable benzothiadiazole-based Eu(iii) metal–organic framework with cco topology has been successfully constructed, and represents the multifunctional fluorescence sensor toward Fe3+, MnO4− and Cr2O72− in aqueous solutions.

Three lanthanide-based MOFs with a pyrene-based carboxylate ligand were solvothermally synthesized, which could be considered as fluorescence sensors toward acetylacetone and aspartic acid via a turn-on effect.

A new benzothiadiazole-based MOF {[Zn(BIBT)(oba)]·DMA}n (JXUST-3, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2oba = 4,4′-oxybisbenzoate) has been solvothermally synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy and TGA. The fluorescence studies suggest that JXUST-3 could simultaneously selectively sense trivalent metal ions including Al3+, Cr3+ and Fe3+ by a turn-off effect, and the detection limits are 0.055, 0.049 and 0.056 μM, respectively. Moreover, JXUST-3 exhibits relatively good thermal and chemical stabilities and reusability. The fluorescent test paper also displayed an obvious turn-off effect, indicating that JXUST-3 can be used as a potential multi-response fluorescent probe. The possible quenching mechanisms of JXUST-3 for Al3+ and Fe3+ were competitive energy absorption, and for Cr3+ ions, they were competitive energy absorption and weak interactions between Cr3+ and the framework. Therefore, JXUST-3 could be viewed as a transition metal MOF fluorescence sensor for Al3+, Cr3+ and Fe3+ by the turn-off effect, simultaneously.

Four new hydrogen-bonded organic frameworks (HOFs) with the formulas {[H4TCPE·bpa]·(CH3OH·H2O)}n (1), {[H4TCPE·bpe]·(CH3OH·0.56H2O)}n (2), {[H4TCPE·bpa]·CH3OH}n (3) and {[H4TCPE·bpe]·(0.41CH3OH·0.59CH3CN)}n (4) (H4TCPE = tetrakis(4-carboxyphenyl)ethylene, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethylene) have been prepared under different conditions and structurally characterized. X-ray crystallographic analysis reveals that the hydrogen bond strengths of 3 and 4 synthesized by solvothermal method are much stronger than those of 1 and 2 prepared by the volatilization method. An obvious fluorescence shift was observed during the sensing process of 3 and 4 toward Al3+ and Fe3+ ions. For HOF 3, a red-shift emission (ca. 28 nm) occurs upon the addition of Al3+ ion. When Al3+ ion is added to HOF 4 in acetonitrile suspension, a red-shift emission (ca. 30 nm) as well as a great fluorescence enhancement happens. Both 3 and 4 exhibit strong fluorescence quenching with high selectivity and sensitivity toward Fe3+ ion. In addition, they display relatively good stabilities as well as reusability. Therefore, HOFs 3 and 4 are excellent fluorescent sensors toward Al3+ and Fe3+ ions.

A novel luminescent CdII-based metal–organic framework {[Cd(BBIP)(TBIP)]·EtOH}n (1) derived from the multidentate 5-tert-butylisophthalic acid (H2TBIP) and the semi-rigid N-donor 3,5-bis(benzimidazol-1-yl)pyridine (BBIP) has been solvothermally synthesized and structurally characterized by using infrared spectroscopy, thermal analysis, single-crystal X-ray diffraction and powder X-ray diffraction. The adjacent CdII ions are linked by two carboxylate groups of one TBIP2− ligand with chelating mode to form a one-dimensional CdII-TBIP2− chain, which is further connected by the BBIP ligand to obtain a two-dimensional network. Interestingly, the fluorescence experiments indicate that 1 could be considered as a good multi-responsive sensing material for detecting Fe3+, MnO4−, Cr2O72−, salicylaldehyde (SA) and ethylenediamine (EDA) via the turn-off effect, with the detection limits of 0.53, 0.98, 3.6, 0.42 and 5.3 ppm, respectively. The luminescence quenching effect induced by Fe3+ could be mainly ascribed to the competitive absorption mechanism. The electron-transfer transition and competitive absorption mechanism could be used to explain the luminescence quenching of MnO4− and Cr2O72−. The turn-off effect of 1 on SA could be ascribed to the photoinduced electron-transfer and competitive absorption mechanisms. Meanwhile, the possible mechanism of fluorescence quenching caused by EDA could be attributed to the structure collapse. More importantly, 1 could be regenerated and reused after five cycles for Fe3+, MnO4−, Cr2O72− and SA detection. In a nutshell, 1 could be employed as a multi-responsive luminescent sensor used for the highly selective and sensitive detection of metal ions, anions and small organic molecules.

A three-dimensional metal–organic framework, namely {[Zn3(BIBT)(BTC)5/3(μ3-OH)]·solvents}n (JXUST-4), has been synthesized by using ZnII ions, and BIBT and H3BTC ligands (BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H3BTC = 1,3,5-benzenetricarboxylic acid). JXUST-4 shows a new (3,3,7)-connected topology net containing a trinuclear ZnII cluster, uncoordinated N atoms of BIBT and uncoordinated carboxylate O atoms of H3BTC, which facilitates the interaction between the framework and analytes. Fluorescence studies indicate that JXUST-4 generates light yellow luminescence, which could be ascribed to ligand-centered emission. More importantly, JXUST-4 could be viewed as an effective fluorescent sensor toward acetylacetone through an obvious fluorescence red-shift with high sensitivity, efficient selectivity, and outstanding recycling capacity. Furthermore, the possible sensing mechanism of JXUST-4 toward acetylacetone is due to electron transfer and weak interactions between the analyte and framework.

Six new coordination polymers (CPs) based on the V-shaped 1,3-bis(benzimidazolyl)benzene (bbib) have been synthesized under solvothermal conditions: [Zn(bbib)(ip)]n (1), {[Zn(bbib)(oba)]·solvents}n (2), {[Zn(bbib)(tp)]·DMF}n (3), [Cd(bbib)(ip)]n (4), {[Cd(bbib)(oba)]·H2O·solvents}n (5) and {[Cd(bbib)(tp)]·DMF}n (6) (ip = isophthalate, oba = 4,4′-oxybisbenzoate and tp = terephthalate). Complexes 1–3 display a plane minimal net, (4,4) sheet and a hexagonal plane net, respectively. The structures of 4–6 range from a 1D zigzag chain (4), 2D (4,4) sheet (5) to a 3D “pillar-layer” coordination framework with pcu α-Po topology (6). The structural transition from 1D to 3D among these complexes is realized with the aid of different auxiliary ligands. The results demonstrate that the conformations and coordination modes of dicarboxylate ligands make an impact on the structural diversity of ZnII/CdII coordination polymers. To the best of our knowledge, the CPs based on the bbib ligand have been successfully prepared for the first time. Moreover, complex 2 is a good bifunctional chemosensor for the detection of both Fe3+ and MnO4− with the detection limits of 3.31 ppm and 8.81 ppm, respectively, indicating that 2 could be used as an efficient fluorescent sensor with high sensitivity and selectivity for Fe3+ and MnO4−.

The hydrothermal reaction of CrO3, Gd2O3 and iminodiacetic acid (H2IDA) yields a three-dimensional (3D) two-fold interpenetrated complex [CrGd(IDA)2(C2O4)]∞ (1). The oxalate anions were generated in situ under hydrothermal conditions. Magnetic studies suggest the presence of weak antiferromagnetic coupling between CrIII and GdIII ions, and negligible GdIII⋯GdIII and CrIII⋯CrIII couplings. Complex 1 exhibits a large magnetocaloric effect with − ΔSmaxm = 39.86 J kg−1 K−1 (the mass aspect) and 93.69 mJ cm−3 K−1 (the volumetric aspect), making it an attractive refrigerant for low-temperature applications.

Single-crystalline nanocubes of SnO2 have been fabricated by oxidation of SnF2 with (NH4)2S2O8 under proper hydrothermal conditions.

Utilizing 2,2′-bipyridine-3,3′-dicarboxylic acid 1,1′-dioxide (H2BDCD) and CuCl2·2H2O (or Ba(NO3)2·6H2O) under hydrothermal conditions produces two novel coordination polymers {[Cu(BDCD)]·EtOH}n, 1 and [Ba(BDCD)·2H2O]n, 2. X-ray structure determination reveals that compound 1 shows a two-dimensional structure which is constructed by a well known (4,8) three-connected bimodal net, compound 2 exhibits a novel three-dimensional structure with interesting barium pillars as building blocks.