•A novel luminescence enhanced sensor for β-hydroxybutyrate (β-HB) is developed based on a Tb3+ complex (TbL2).•A 1:1 binding model between TbL2 and β-HB is proposed.•The binding constant of TbL2-β-HB is 9.3 × 105 M−1.A novel Tb3+ complex (Tb(C14H10O4)⋅Cl, TbL2) based on benzoic acid (L+H) was successfully synthesized, and gave a weak green emission in methanol–water (V:V, 4:1, pH 4.49). With the addition of β-hydroxybutyrate (β-HB) to a semi-aqueous solution of TbL2, an increment of the luminescent intensity at 545 nm assigned to 5D4 → 7F5 transition of Tb3+ was measured, which was evident to the naked eye. The response showed high selectivity for β-HB compared with other common anions including Cl−, NO3-, CO32-, PO43-, HPO42-, H2PO4-, C2O42-, P2O74-, SO42-, lactate, AcO−, citrate, malate therefore it has the potential to be applied as a luminescent sensor for β-HB.The luminescent responses of TbL2 (0.08 mM) with various anions in methanol -water (V:V, 4:1, pH 4.49). Bars represent the relative luminescence intensity ratio of 545 nm to 485 nm of TbL2 (0.08 mM) with the addition of 3 equivalent various common anions. (λex = 240 nm)

A novel Eu3+ complex (EuL) based on 1,10-phenanthroline-2-carboxylic was successfully synthesized, and gave a characteristic red emission. The complex was shown to act as a selective luminescence quencher for Fe3+, as shown by the “on/off” switch phenomenon. The quenching curve showed a double-exponential well decay with the increase of Fe3+ ions. The stability constant of EuL/Fe3+ was calculated as 8.6 × 103 L mol−1(lg β/L mol−1 = 3.93). The response showed high selectivity for Fe3+ compared with other metal ions; the complex therefore has the potential to be applied as a fluorescent sensor for Fe3+.Graphical abstractHighlights► A novel Fe3+ luminescent “on–off” sensor is developed based on a Eu3+ complex. ► A 1:1 binding model between the Eu3+ complex and the Fe3+ ion is proposed. ► The binding constant of EuL/Fe3+ is 8.6 × 103 L mol−1(lg β/L mol−1 = 3.93).

A phosphorescent probe, Ir(ppy)2Cl(DMF) (Ir2), for cysteine (Cys) is reported. The recognition is based on the time-dependent emission of Ir2-Cys. Importantly, this probe can discriminate Cys rapidly from homocysteine (Hcy). Probe Ir2 displays a highly selective 72 nm of luminescent red-shift toward Cys within 30 min with an obvious emissive color change from green to orange. After 30 min, the emission band blue shifts gradually with an emissive change from orange to green. TDDFT combined with CV studies indicates that the different emission profile is ascribed to the different binding modes of Ir2 to Cys with time. The probe can be used to determine Cys in semiaqueous solution.

A ruthenium polypyridine complex [Ru(phen)2(IPBA)](PF6)2 (complex 1) (IPBA = 4-(1H-imidazo[4,5-f][1,9]phenanthroline-2-yl)benzaldehyde), which displays environment-responsive dual emissive properties, was designed and synthesized. In aprotic solvent, such as DMSO, DMF or CH3CN, the complex emits strong cyan light. When in protic solvent, it emits orange light. Similarly, the response of the complex to homocysteine and cysteine (Hcy/Cys) also shows obvious solvent dependence. TDDFT calculations reveal that the protonation of imidazole nitrogen in protic solution is responsible for the luminescent red shift. Hence, the complex could be used to detect Hcy/Cys in aprotic solvent, as well as in protic solvent.

A novel compound, 2-p-tolyl-1H-imidazo[4,5-f][1,10]phenanthrolinium hydrogenselenite (HMPIP·HSeO3, C1), shows a peculiar OFF–ON fluorescent response to Zn2+ in aqueous solution and living cells.

The binding of two Co(III) complexes [Co(phen)2(DPQ)]3+ and [Co(phen)2(HPIP)]Cl3 [HPIP = 2-(2-hydroxyphenyl) imidazo [4,5-f][1,10] phenanthroline, DPQ = dipyrido[3,2-f:2′,3′-h]quinoxaline] to the normal base-paired decanucleotide d(CCTAATTAGG)2 was studied by 2D NMR. The results indicate that the width of intercalating ligand has a large effect on the selectivity of binding site. For [Co(phen)2(HPIP)]Cl3, the complex binds the decanucleotide at C2T3:G9A8 and A4A5:T7T6 by intercalation from the minor groove, while [Co(phen)2(DPQ)]3+ intercalates into T3A4:T7A8 region from the minor groove. The conclusion was further proved by molecular modeling.The ligand-structure-selective binding of oligonucleotide by cobalt complexes was proved by 2D NMR.

The binding of the complex [Co(phen)2(DPQ)]Cl3 to the decanucleotide d(CCGAATGAGG)2 containing two pairs of sheared G:A mispairs was studied by 2D-NMR. There appear many 1H NOE cross-peaks from the complex to the oligonucleotide. The results indicate that the complex, with DPQ, intercalates into the oligonucleotide via its terminal base pairs from the minor groove, which further proved our previous conclusion.The terminal binding of [Co(phen)2(DPQ)]Cl3 to d(CCGAATGAGG)2 containing two pairs of sheared G:A mispair was proved by 2D-NMR.

A novel cis-platinum analog Pt(HPIP)Cl2 (HPIP = 2-(2-hydroxyphenyl)imidazo[4, 5-f] [1, 10]phenanethroline) has been synthesized and characterized. NMR and UV experiments show that the complex can interact with mononucleotide in a way different from that of cis-platinum

An independent catalyst layer is applied to develop a highly effective way to reduce coking when operating in methane based fuels, in which the catalyst layer is separated from a Ni cermet anode. In this way, Ni cermet anode conductivity is not influenced, and cell cracking due to the thermal–mechanical stress from the mismatched thermal expansion coefficients (TECs) between the catalyst and anode materials, the temperature gradients within the anode caused by the highly endothermic reforming reaction of methane, and the large internal strain during the reduction process is also avoided. La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF), which is co-pressed with an Al2O3 substrate into a double-layered slice with a mesoporous structure, functions as an independent catalyst layer of the Ni-based anode. Under SOFC operating conditions, a K2NiF4-type oxide (Sr,La)FeO4 with homogeneously dispersed CoFe alloy nanoparticles is formed, which shows good catalytic activity for methane partial oxidation with 88% conversion at 950 °C in a mixture of CH4 and O2 (1:1). A conventional cell with the state-of-art Ni cermet anode (NiO–8% Y stabilized ZrO2 (YSZ)/YSZ/La0.8Sr0.2MnO3–YSZ) is constructed and the electrochemical performance of cells with and without the independent catalyst layer is tested. In wet methane, the voltage of the conventional cell without the catalyst layer declines rapidly from 0.7 V to 0.1 V within 20 min at 333 mA cm−2 and 800 °C. In contrast, the voltage of the modified cell with an independent catalyst layer stabilizes at 0.79 V with negligible degradation within 116 h. In wet coal bed methane (CBM), the voltage of the modified cell with an independent catalyst layer exhibits a slow decrease from 0.69 V to 0.66 V within 12 h. The stable power output of the cell with an independent catalyst layer under a constant current load in methane indicates excellent coking resistance. The microstructure and surface composition of the catalyst layer and anode are further analyzed by SEM and EDX after the stability test.

A novel compound, 2-p-tolyl-1H-imidazo[4,5-f][1,10]phenanthrolinium hydrogenselenite (HMPIP·HSeO3, C1), shows a peculiar OFF–ON fluorescent response to Zn2+ in aqueous solution and living cells.

A ruthenium polypyridine complex [Ru(phen)2(IPBA)](PF6)2 (complex 1) (IPBA = 4-(1H-imidazo[4,5-f][1,9]phenanthroline-2-yl)benzaldehyde), which displays environment-responsive dual emissive properties, was designed and synthesized. In aprotic solvent, such as DMSO, DMF or CH3CN, the complex emits strong cyan light. When in protic solvent, it emits orange light. Similarly, the response of the complex to homocysteine and cysteine (Hcy/Cys) also shows obvious solvent dependence. TDDFT calculations reveal that the protonation of imidazole nitrogen in protic solution is responsible for the luminescent red shift. Hence, the complex could be used to detect Hcy/Cys in aprotic solvent, as well as in protic solvent.