•Fe and N co-doped carbon dots (Fe-N-CDs) were synthesized for the first time.•Characterizations of obtained Fe-N-CDs were thoroughly investigated.•The Fe-N-CDs exhibited a superior peroxidase activity due to the iron doping.•As the nanozyme, Fe-N-CDs were successfully applied in immunosorbnent assay with an improved result for CEA detection.Herein, iron and nitrogen co-doped carbon dots (Fe-N-CDs) were synthesized through a solvothermal method assisting with the microwave synthesis system for the first time. Multiple techniques were employed to characterize the properties of the obtained particles. The emphasis of current work was the confirmation of their intrinsic peroxidase activity due to the Fe doping, which is similar to natural ferriporphyrin. Through catalyzing the oxidization of 3,3′,5,5′-Tetramethylbenzidine (TMB) in the presence of H2O2, the Fe-N-CDs exhibited a superior catalytic performance over horseradish peroxidase (HRP), suggesting their potential applications in catalytic area. Furthermore, the Fe-N-CDs were coupled to antibody as the biocatalyst instead of HRP (commonly used in enzyme-linked immunosorbnent assay (ELISA)). Results of carcinoembryonic antigen (CEA) determination demonstrated the feasibility of this approach, a detection limit as low as 0.1 pg/mL within 5 min has been achieved. These advances may trigger research interest in Fe-N-CDs and their new applications in various fields.

•We designed an electrochemical biosensor for lead ion.•Hemin/G-quadruplex was used as NADH oxidase and HRP-mimicking DNAzyme.•Porous Au–Pd bimetallic nanostructures were employed as nanocarriers.In this work, a sensitive and specific electrochemical biosensor for lead ion (Pb2+) detection was developed by coupling with synergetic catalysis of porous Au–Pd bimetallic nanoparticles and hemin/G-quadruplex-based DNAzyme. In the presence of target Pb2+, the substrate strand was cleaved and the enzyme strand was released. Subsequently, G-rich DNA-labeled Au–Pd bimetallic nanoparticle was linked with the released enzyme strand through the helper DNA. Upon addition of hemin, a large number of hemin/G-quadruplex-based DNAzyme molecules were formed on the electrode to serve as nicotinamide adenine dinucleotide hydrogen (NADH) oxidase and peroxidase mimics. DNAzyme could catalyzed the reduction of H2O2, generated from NADH in the presence of O2, to produce an electrochemical signal when using thionine as the electron mediator. Introduction of porors Au–Pd bimetallic nanoparticles could enhance the detectable signal and cause the increase in the sensitivity. Experimental results showed that the variations (∆I) in the cathodic peak currents of the biosensor were linearly dependent on target Pb2+ concentrations from 1.0 pM to 100 nM with a detection limit (LOD) of 0.34 pM. The excellent performance of the sensing platform indicated its promising prospect as a valuable tool for simple and cost-effective Pb2+ detection in practical application.

Two windmill-like Ag3Cu5 alkynyl clusters were synthesized and characterized. They display novel PL and ECL properties, which could be modified by changing the substituent on the alkynyl ligands. According to the study of electrochemical behaviours, ECL behaviours and ECL emission spectra of the Ag3Cu5 clusters, a possible ECL mechanism was proposed.

•Tiopronin was employed as a new co-reactant for Ru(bpy)32+ ECL system.•A sensitive ECL method was established for the direct detection of tiopronin.•This method has advantages of both high sensitivity and simple procedure.•A possible mechanism was proposed for Ru(bpy)32+ /tiopronin system.It was found that tiopronin could strongly enhance the electrochemiluminescence of tris(2,2’-bipyridine) ruthenium(II) (Ru(bpy)32+) in alkaline solution on a bare Pt electrode, based on which a sensitive, simple and rapid method for the determination of tiopronin was established. Under the optimal conditions, the logarithm of ECL enhancement has a linear relationship with the logarithm of tiopronin concentration in the range from 2.0×10−7 to 2.0×10−4 mol L−1 with a detection limit of 1.0×10−8 mol L−1 (S/N= 3), and the relative standard deviation of 1.6% (n=7, c=5.0×10−6 mol L−1). The proposed method has been applied to the determination of tiopronin in pharmaceutical preparations and the results were satisfactory with recoveries of 91.7±1.7%, 98.3±1.0% and 100.8±0.5%, respectively, for three different concentration levels (0.61 μmol L−1, 6.1 μmol L−1 and 12.2 μmol L−1). According to the study of electrochemical behavior, ECL behavior and ECL emission spectrum of Ru(bpy)32+/tiopronin system, a possible ECL mechanism was proposed.

Two novel luminescent hetero-trinuclear complexes [Pt2Ag(μ-dpppy)2(CCC6H4R-4)4](ClO4) (R = H, 1; R = CH3, 2; dpppy = 2,6-bis(diphenylphosphino)pyridine) were synthesized by the self-assembly reaction between [Pt(CCC6H4R-4)4]2− and [Ag2(μ-dpppy)3]2+ and characterized by elemental analyses, electrospray ionization mass spectrometry, and 1H NMR and 31P{1H} NMR spectroscopy and by X-ray crystallography for complex 2. Two Pt2Ag complexes show strong luminescence in the solid state, but exhibit weak emission in CH2Cl2 solution and in acetonitrile–water (1:1, v:v) solution at room temperature. To overcome the limitations of low water solubility and weak emission in solutions, a new kind of luminescent Pt2Ag@SiO2 nanoparticles was prepared by incorporating the new Pt2Ag acetylides into monodisperse silica nanoparticles. It is noted that Pt2Ag@SiO2 nanoparticles exhibit strong luminescence in aqueous solution, and cyanide anions tend to decrease their luminescence intensity in NaHCO3–NaOH buffer solution. Based on this, a novel nanosensor for highly sensitive detection of cyanide anions was developed in the range of 0.1–10.0 μM.

The four heteronuclear clusters [Ag2Au2(μ-dpppy)3(C≡CC6H4R-4)2](ClO4)2 (R = H (1) CH3 (2), COOCH3 (3), CHO (4)) were prepared by the self-assembly reaction between (AuC≡C6H4R-4)n (R = H, CH3, COOCH3, CHO) and [Ag2(μ-dpppy)3]2+ (dpppy = 2,6-bis(diphenylphosphino)pyridine) and characterized by elemental analyses, electrospray ionization mass spectrometry (ESI-MS), and 1H NMR and 31P{1H} NMR spectroscopy and by X-ray crystallography for 1, 3, and 4. It is revealed that the complexes exhibit bright blue (1–3) and green (4) luminescence in the solid state and in solution with the luminescent lifetimes in the microsecond range, indicating that the luminescence is most likely associated with a spin-forbidden triplet parentage. Interestingly, only complex 4 displays distinctly mechanical grinding responsive emission switching. The recognition interactions of complex 4 containing aldehyde groups with homocysteine (Hcy) and cysteine (Cys) have been studied by UV–vis and emission titrations. A strong luminescence quench was found upon reaction of complex 4 only with Hcy or Cys, but not with other amino acids, proteins, and common anions, indicating a high specificity for recognition of Hcy and Cys.

Two hexanuclear clusters, [Pt2Ag4(C≡CC6H4R)8] (R = CH3, 1; R = H, 2), together with dimer [Pt2Ag4(C≡CC6H5)8]2 (3), have been synthesized and characterized by elemental analyses, electrospray ionization mass spectrometry, and 1H NMR spectroscopy and by X-ray crystallography for 1 and 3. A considerable enhancement of photoluminescence (PL) and a notable red shift in the emission maximum of 1 (λmax 600 nm) relative to 2 (λmax 545 nm) are observed. Electrogenerated chemiluminescence (ECL) of 1 and 2 in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) at different working electrodes in different solvents (CH2Cl2, CH2ClCH2Cl, or CH3CN) has been studied. The ECL spectra are identical with the PL spectra, indicating that ECL emissions are also due to a MLM′CT [Pt(d)/π (C≡CC6H4R-4) → Pt(pz)/Ag(sp)/π* (C≡CC6H4R-4)] state modified by Pt···Ag and Ag···Ag contacts. ECL of 1- and 2/amine systems in CH2ClCH2Cl was produced at the potentials of 1.14–1.19 V vs SCE, notably negatively shifted by about 0.38 V compared to those of the Ru(bpy)32+/amine system. In all cases, ECL quantum efficiencies of 2 are higher than those of 1 and on the same order of magnitude as that of the [Ru(bpy)3](PF6)2/amine system. It is noted that Sudan I tends to decrease the ECL intensity of the 1/DBAE system in CH2ClCH2Cl at a platinum working electrode. A new ECL method for the determination of Sudan I was developed with a linear range of 2.5 × 10–5–1.0 × 10–3 M and a detection limit of 8.0 × 10–6 M based on 3 times the ratio of signal-to-noise.

A series of dinuclear compounds of [Ru(bpy)2(tpphz)Ln(TTA)3](PF6)2 (tpphz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:3′′′,4′′′-j]phenazine; Ln = Er(III), Nd(III), Yb(III) and Gd(III); TTA = 2-thenoyltrifluoroacetone) have been prepared by attachment of a [Ln(TTA)3] fragment at the vacant diimine site of the luminescent mononuclear complex [Ru(bpy)2(tpphz)](PF6)2. In the solid state, in CH2Cl2 solution and in Tris-HCl buffer solution of these dinuclear complexes Ru–Ln, sensitized near-infrared (NIR) luminescence is observed from Nd and Yb centres following excitation of the d-block unit, which results from the effective Ru → Ln (Ln = Nd, Yb) energy transfer, but no Er-based NIR luminescence is produced. The 3MLCT (MLCT = metal to ligand charge transfer) emission is partly quenched in the Ru–Nd complex, slightly increased in the Ru–Yb complex, and is not changed in the Ru–Er complex. Interestingly, alpha-fetal protein (AFP) tends to decrease the NIR luminescence intensity of the Ru–Nd complex in Tris-HCl buffer solution. A novel NIR luminescent method for the determination of AFP was developed with a linear range of 0.5–18 ng mL−1, and a detection limit of 0.2 ng mL−1 based on 3 times the ratio of the signal-to-noise. Considering the attractive features, such as good selectivity, stability and rapidity, the proposed NIR luminescent method provides promising potential for AFP detection in clinical diagnosis and biomedical applications.

Three rhenium carbonyl complexes 1–3 were synthesized by reaction of the appropriate bidentate pyrazolyl–pyridyl-based ligand L1, L2 (L1 = 2-[1-{4-(bromomethyl)benzyl}-1H-pyrazol-3-yl]pyridine; L2 = 1,4-bis(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene) with [Re(CO)5Cl] in toluene. They were characterized by elemental analyses, ESI–MS, 1H spectroscopy, and X-ray crystallography for 1 and 2. Compounds 1–3 exhibit bright yellow–green luminescence in the solid state and in solution at 298 K with the lifetimes in the microsecond range. It is noteworthy that the luminescent quantum efficiencies of compounds 1–3 are between 0.040 and 0.051, which are much higher than that of the [Re(bpy)(CO)3Cl] complex (= 0.019) (M. M. Richter et al., Anal. Chem., 1996, 68, 4370; J. Van Houten et al., J. Am. Chem. Soc., 1976, 98, 4853). Electrogenerated chemiluminescence (ECL) was observed in solutions of these complexes in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) by stepping the potential of a Pt disk working electrode. The ECL spectra are identical to the photoluminescence spectra, indicating that the chemical reactions following electrochemical oxidation or reduction form the same 3MLCT excited states as that generated in the photoluminescence experiments. In most cases, the ECL quantum efficiencies of complexes 1–3 are comparable to that of the [Re(L)(CO)3Cl] (L = bpy or phen) system. Oxygen tends to substantially decrease ECL intensities of the three rhenium complexes–TPrA system, which could allow them to be used as oxygen sensors.

Mononuclear ruthenium complex 1 and dinuclear complex 2 were synthesized by reaction of the appropriate bidentate pyrazolyl-pyridyl-based ligand L (L = 1,4-bis(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene) with cis-Ru(bipy)2Cl2·2H2O. They were characterized by elemental analyses, ESI-MS, 1H spectroscopy, and X-ray crystallography for 2. Compounds 1 and 2 both emit strongly in solid states and in solutions at 298 K with the lifetimes in the microsecond range. Electrogenerated chemiluminescence (ECL) of complexes 1 and 2 in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) at different working electrodes in acetonitrile and phosphate buffer solutions (PBS, pH 7.5) was studied. The ECL spectra are identical to the photoluminescence spectra, indicating that the ECL emissions are due to the metal to ligand charge transfer (MLCT). In all cases, ECL quantum efficiencies of dinuclear complex 2 are higher than those of mononuclear complex 1, and ECL quantum efficiencies of complexes 1 and 2/TPrA system are higher than those of DBAE system. It is noted that diuretic furosemide tends to decrease the ECL intensity of complex 2/TPrA system in PBS (pH 7.5) at GC working electrode. A novel ECL method for the determination of diuretic furosemide was developed with a linear range between 2.0 × 10−7 mol L−1 and 1.0 × 10−6 mol L−1, and a detection limit of 1.2 × 10−8 mol L−1 based on 3 times the ratio of signal-to-noise.

In this paper, it was found that Ru(H2bpp)2(PF6)2 (H2bpp = 2,6-bis(pyrazol-3-yl)pyridine) complex had excellent electrochemical activity at the carbon paste electrode in the buffer solution of Tris–HCl (pH 7.0) with a couple reversible redox peaks at 0.296 V and 0.348 V, respectively. Voltammetry was used to investigate the electrochemical behavior of Ru(H2bpp)2(PF6)2 and the interaction between Ru(H2bpp)2(PF6)2 and bovine serum albumin (BSA). In the present of BSA, the oxidation peak current of Ru(H2bpp)2(PF6)2 complex was decreased linearly and the decrease of oxidation peak current of Ru(H2bpp)2(PF6)2 is proportional to BSA concentration from 0.1 to 2.5 mg/L with a detection limit 0.02 mg/L.

•Coordination containers with deeper π-rich exo-cavities are designed and prepared.•Incorporating the phenyl groups gives rise to higher overall porosity.•The supercontainer exhibits excellent CO2/O2 and CO2/N2 adsorption selectivity.Two new coordination supercontainers have been successfully isolated from the self-assembly reactions of the container precursor p-phenylsulfonylcalix [4]arene, Ni(II) or Co(II) ion, and diphenylmethane-4,4'-dicarboxylic acid. Crystal structure analysis revealed that these two coordination supercontainers possess a similar endo cavity and two deeper exo cavities compared to the related supercontainers based on p-tert-butylsulfonylcalix [4]arene. Gas and vapor adsorption studies indicated that the new compounds are permanently porous and show much better CO2/O2 and CO2/N2 selectivity and higher vapor adsorption than the tert-butyl analogues.Two new coordination supercontainers with deeper π-rich exo-cavities have been successfully synthesized. The solid-state porosity is successfully modulated by incorporating extended phenyl groups at the upper rim, giving rise to excellent gas/vapor adsorption capacity and N2/CO2 and O2/CO2 gas separation.

Two windmill-like Ag3Cu5 alkynyl clusters were synthesized and characterized. They display novel PL and ECL properties, which could be modified by changing the substituent on the alkynyl ligands. According to the study of electrochemical behaviours, ECL behaviours and ECL emission spectra of the Ag3Cu5 clusters, a possible ECL mechanism was proposed.

A series of dinuclear compounds of [Ru(bpy)2(tpphz)Ln(TTA)3](PF6)2 (tpphz = tetrapyrido[3,2-a:2′,3′-c:3′′,2′′-h:3′′′,4′′′-j]phenazine; Ln = Er(III), Nd(III), Yb(III) and Gd(III); TTA = 2-thenoyltrifluoroacetone) have been prepared by attachment of a [Ln(TTA)3] fragment at the vacant diimine site of the luminescent mononuclear complex [Ru(bpy)2(tpphz)](PF6)2. In the solid state, in CH2Cl2 solution and in Tris-HCl buffer solution of these dinuclear complexes Ru–Ln, sensitized near-infrared (NIR) luminescence is observed from Nd and Yb centres following excitation of the d-block unit, which results from the effective Ru → Ln (Ln = Nd, Yb) energy transfer, but no Er-based NIR luminescence is produced. The 3MLCT (MLCT = metal to ligand charge transfer) emission is partly quenched in the Ru–Nd complex, slightly increased in the Ru–Yb complex, and is not changed in the Ru–Er complex. Interestingly, alpha-fetal protein (AFP) tends to decrease the NIR luminescence intensity of the Ru–Nd complex in Tris-HCl buffer solution. A novel NIR luminescent method for the determination of AFP was developed with a linear range of 0.5–18 ng mL−1, and a detection limit of 0.2 ng mL−1 based on 3 times the ratio of the signal-to-noise. Considering the attractive features, such as good selectivity, stability and rapidity, the proposed NIR luminescent method provides promising potential for AFP detection in clinical diagnosis and biomedical applications.

Two novel luminescent hetero-trinuclear complexes [Pt2Ag(μ-dpppy)2(CCC6H4R-4)4](ClO4) (R = H, 1; R = CH3, 2; dpppy = 2,6-bis(diphenylphosphino)pyridine) were synthesized by the self-assembly reaction between [Pt(CCC6H4R-4)4]2− and [Ag2(μ-dpppy)3]2+ and characterized by elemental analyses, electrospray ionization mass spectrometry, and 1H NMR and 31P{1H} NMR spectroscopy and by X-ray crystallography for complex 2. Two Pt2Ag complexes show strong luminescence in the solid state, but exhibit weak emission in CH2Cl2 solution and in acetonitrile–water (1:1, v:v) solution at room temperature. To overcome the limitations of low water solubility and weak emission in solutions, a new kind of luminescent Pt2Ag@SiO2 nanoparticles was prepared by incorporating the new Pt2Ag acetylides into monodisperse silica nanoparticles. It is noted that Pt2Ag@SiO2 nanoparticles exhibit strong luminescence in aqueous solution, and cyanide anions tend to decrease their luminescence intensity in NaHCO3–NaOH buffer solution. Based on this, a novel nanosensor for highly sensitive detection of cyanide anions was developed in the range of 0.1–10.0 μM.

Three rhenium carbonyl complexes 1–3 were synthesized by reaction of the appropriate bidentate pyrazolyl–pyridyl-based ligand L1, L2 (L1 = 2-[1-{4-(bromomethyl)benzyl}-1H-pyrazol-3-yl]pyridine; L2 = 1,4-bis(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene) with [Re(CO)5Cl] in toluene. They were characterized by elemental analyses, ESI–MS, 1H spectroscopy, and X-ray crystallography for 1 and 2. Compounds 1–3 exhibit bright yellow–green luminescence in the solid state and in solution at 298 K with the lifetimes in the microsecond range. It is noteworthy that the luminescent quantum efficiencies of compounds 1–3 are between 0.040 and 0.051, which are much higher than that of the [Re(bpy)(CO)3Cl] complex (= 0.019) (M. M. Richter et al., Anal. Chem., 1996, 68, 4370; J. Van Houten et al., J. Am. Chem. Soc., 1976, 98, 4853). Electrogenerated chemiluminescence (ECL) was observed in solutions of these complexes in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) by stepping the potential of a Pt disk working electrode. The ECL spectra are identical to the photoluminescence spectra, indicating that the chemical reactions following electrochemical oxidation or reduction form the same 3MLCT excited states as that generated in the photoluminescence experiments. In most cases, the ECL quantum efficiencies of complexes 1–3 are comparable to that of the [Re(L)(CO)3Cl] (L = bpy or phen) system. Oxygen tends to substantially decrease ECL intensities of the three rhenium complexes–TPrA system, which could allow them to be used as oxygen sensors.

Mononuclear ruthenium complex 1 and dinuclear complex 2 were synthesized by reaction of the appropriate bidentate pyrazolyl-pyridyl-based ligand L (L = 1,4-bis(3-(2-pyridyl)pyrazol-1-ylmethyl)benzene) with cis-Ru(bipy)2Cl2·2H2O. They were characterized by elemental analyses, ESI-MS, 1H spectroscopy, and X-ray crystallography for 2. Compounds 1 and 2 both emit strongly in solid states and in solutions at 298 K with the lifetimes in the microsecond range. Electrogenerated chemiluminescence (ECL) of complexes 1 and 2 in the absence or presence of coreactant tri-n-propylamine (TPrA) or 2-(dibutylamino)ethanol (DBAE) at different working electrodes in acetonitrile and phosphate buffer solutions (PBS, pH 7.5) was studied. The ECL spectra are identical to the photoluminescence spectra, indicating that the ECL emissions are due to the metal to ligand charge transfer (MLCT). In all cases, ECL quantum efficiencies of dinuclear complex 2 are higher than those of mononuclear complex 1, and ECL quantum efficiencies of complexes 1 and 2/TPrA system are higher than those of DBAE system. It is noted that diuretic furosemide tends to decrease the ECL intensity of complex 2/TPrA system in PBS (pH 7.5) at GC working electrode. A novel ECL method for the determination of diuretic furosemide was developed with a linear range between 2.0 × 10−7 mol L−1 and 1.0 × 10−6 mol L−1, and a detection limit of 1.2 × 10−8 mol L−1 based on 3 times the ratio of signal-to-noise.