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In this paper, two dual function fluorescent probes P1 and P2 with obvious fluorescence spectrum change were developed for the detection of Zn2+ and H2S. Density functional theory (DFT) was employed to investigate the detection mechanism. A further illustration of the fluorescence quenching mechanism was also studied by 1H NMR titration and UV‐Vis absorption spectroscopy. Both probes are new compounds containing coumarin structure as fluorophore. They can quantitatively detect Zn2+ and H2S in the concentration range from 0 to 50 μM with excellent selectivity and anti‐interference ability over many metal ions or anions. Most worthy is that probes P1 and P2 have better cell permeability with lower cytotoxicity, which can be used for fluorescence detection in MCF‐7 cells, as well as the detection of exogenous Zn2+ in organisms. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel 1,3,4-oxadiazole derivatives were prepared and fully characterized. [•] UV–vis absorption and fluorescence spectroscopy of all compounds were measured. [•] The minimized structures, the molecular orbital (HOMO and LUMO) energies and the orbital maps of compound 5a –g were calculated. [Copyright &y& Elsevier]

Abstract: The interactions of Cu2+ with urease were investigated by fluorescence, UV/vis, CD, synchronous fluorescence, and three-dimensional fluorescence spectra techniques. Cu2+ effectively quenched the intrinsic fluorescence of urease via static quenching. The binding constant K A, the binding site n and the thermodynamic parameters are obtained. The process of binding Cu2+ to urease was a spontaneous molecular interaction procedure with electrostatic interaction. The conformation of urease was discussed by UV/vis, CD, synchronous and three-dimensional fluorescence techniques. [Copyright &y& Elsevier]

Abstract: The interactions between human hemoglobin and orange I (or orange II) were investigated by UV/vis absorption, circular dichroism, fluorescence spectra techniques, and molecular modeling method. Orange I and orange II effectively quenched the intrinsic fluorescence of human hemoglobin by static quenching. The processes of the binding orange I and orange II on human hemoglobin were spontaneous molecular interaction procedure with hydrogen bonds, van der Waals force, hydrophobic and electrostatic interactions according to van’t Hoff equation and molecular modeling. There is a single class of binding site of orange I (orange II) in human hemoglobin and the molecular modeling study shows that orange I and orange II are dipped into α2 chain. The results of CD, synchronous fluorescence and three-dimensional fluorescence spectra indicated a small loss of α-helical secondary structure of human hemoglobin induced by orange I and orange II. [Copyright &y& Elsevier]

Abstract: The nature of the interaction between human hemoglobin and C.I. acid red 27 was investigated systematically by ultraviolet–vis absorbance, circular dichroism, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques at pH 7.40. The quenching mechanism, binding constants, and the number of binding sites were determined by the quenching of human hemoglobin fluorescence in presence of C.I. acid red 27. The results showed that the nature of the quenching was of static type and the process of binding acid red 27 on human hemoglobin was a spontaneous molecular interaction procedure. The electrostatic and hydrophobic interactions played a major role in stabilizing the complex; The distance r between donor and acceptor was obtained to be 4.40nm according to Förster’s theory; The effect of acid red 27 on the conformation of human hemoglobin was analyzed using synchronous fluorescence, circular dichroism and three-dimensional fluorescence spectra. [Copyright &y& Elsevier]

Abstract: The interaction of benzidine (BEN) with trypsin was studied by fluorescence spectrum. It was shown that BEN has quenched the fluorescence launching from trypsin by reacting with it and forming a certain kind of new complex. The quenching and energy transfer mechanisms were discussed. The binding constants and thermodynamic parameters at three different temperatures, the binding locality, and the binding power were obtained. The conformation of trypsin was discussed by synchronous and three-dimensional fluorescence techniques. [Copyright &y& Elsevier]

Abstract: The interaction between bisphenol A (BPA) and lysozyme (or trypsin) was investigated by UV–vis absorption, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. BPA effectively quenched the intrinsic fluorescence of lysozyme and trypsin via static quenching. H-bonds and van der Waals interactions played a major role in stabilizing the BPA–proteinase complex. The distance r between donor and acceptor was obtained to be 1.65 and 2.26nm for BPA–lysozyme and BPA–trypsin complexes, respectively. The effect of BPA on the conformation of lysozyme and trypsin was analyzed using synchronous fluorescence and three-dimensional fluorescence spectra. [Copyright &y& Elsevier]

Abstract: The interaction between human serum albumin (HSA) and pentachlorophenol (PCP) was investigated by UV/vis absorption, circular dichroism (CD), fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. PCP effectively quenched the intrinsic fluorescence of HSA via static quenching. The process of binding PCP on HSA was a spontaneous molecular interaction procedure. The hydrophobic interaction played a major role in stabilizing the PCP–HSA complex. The distance r between donor and acceptor was obtained to be 3.35nm according to Förster’s theory. The binding site of PCP to HSA mainly located within hydrophobic cavity between domain II and domain I. The effect of PCP on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy, CD and three-dimensional fluorescence spectra. [Copyright &y& Elsevier]

Abstract: The interaction of benzidine (BZ) with hemocyanin (Hc) from Chinese mitten crab (Eriocheir japonica sinensis) was studied by fluorescence spectrum. BZ can quench the fluorescence of Hc by forming a new complex. The process of binding BZ on Hc was a spontaneous molecular interaction procedure. The thermodynamic parameters, the enthalpy change and entropy change were estimated to be 47.36kJmol−1, 248.51Jmol−1 K−1 according to the van’ Hoff equation. This indicates that hydrophobic interaction played a major role in stabilizing the complex. The results of synchronous fluorescence spectroscopy and three-dimensional fluorescence spectra indicated that the structure of these tyrosine residues environments was altered by BZ, which could enter into the hydrophobic pocked of Hc. [Copyright &y& Elsevier]

Abstract: The interaction between bovine haemoglobin and C.I. Solvent Red 24 was investigated by UV/vis absorption, fluorescence, resonance light-scattering spectra, synchronous fluorescence as well as three-dimensional fluorescence spectra techniques at pH 7.4. The dye effectively quenched the intrinsic fluorescence of bovine haemoglobin via static quenching. The process of dye to bovine haemoglobin was spontaneous, the related changes in enthalpy and entropy being 1.78 kJ mol−1, 81.58 J mol−1 K−1 respectively, according to the van''t Hoff equation, indicating that hydrophobic interaction played a major role in stabilizing the complex. Synchronous fluorescence spectroscopy and three-dimensional fluorescence spectra showed that the structure of the tyrosine residue environments was altered by the dye which interacted at the α1β2 interface of the bovine haemoglobin molecule. [Copyright &y& Elsevier]

Abstract: Caffeine (CF) is a member of the methylxanthine family with numerous biological activities, which may contribute to the prevention of human disease but also may be potentially harmful. In the present study, the interaction of CF with bovine hemoglobin (BHb) under physiological condition was studied by fluorescence and UV/vis spectroscopy. Fluorescence data revealed that the fluorescence quenching of BHb by CF was the result of the formed complex of CF–BHb. The binding constants and thermodynamic parameters at three different temperatures, the binding position, and the binding force were determined. The hydrophobic and hydrogen bonds interactions were the predominant intermolecular forces to stabilize the complex. The conformation of BHb was discussed by synchronous fluorescence techniques. The synchronous spectra indicated that the structures of the Tyr and Try residues environments were altered and the physiological functions of BHb were affected by 0. This study provides important insight into the mechanism of erythrocyte sickling, which may be a useful guideline for further toxicology investigation. [Copyright &y& Elsevier]

Abstract: The interaction between bovine hemoglobin (BHb) and Fe3O4 colloid was investigated by UV/vis absorption, FT-IR, fluorescence, resonance light scattering spectra, CD, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. Fe3O4 effectively quenched the intrinsic fluorescence of BHb via static quenching. The process of binding Fe3O4 on BHb was a spontaneous molecular interaction procedure. The thermodynamic parameters indicate that van der Waals and hydrogen bonds, electrostatic interactions played a major role in stabilizing the Fe3O4–BHb complex. The effect of Fe3O4 on the conformation of BHb was analyzed using CD and synchronous fluorescence spectroscopy. [Copyright &y& Elsevier]

Abstract: The interaction between bovine hemoglobin (BHb) and phosphomolybdate acid (PMo12) was investigated by UV/vis absorption, IR, circular dichroism (CD), fluorescence, resonance light scattering spectra, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. PMo12 effectively quenched the intrinsic fluorescence of BHb via static quenching. The process of binding PMo12 on BHb was a spontaneous molecular interaction procedure. The thermodynamic parameters, ΔH° and ΔS° were estimated to be 28.69KJmol−1, 158.20Jmol−1 K−1 according to the van’ Hoff equation. This indicates that hydrophobic interaction played a major role in stabilizing the PMo12–BHb complex. The effect of PMo12 on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy, IR and CD spectra. [Copyright &y& Elsevier]

Abstract: The interaction between imidacloprid (IMI) and human serum albumin (HSA) was investigated using fluorescence and UV/vis absorption spectroscopy. The experimental results showed that the fluorescence quenching of HSA by IMI was a result of the formation of IMI–HSA complex; static quenching was confirmed to result in the fluorescence quenching. The apparent binding constant K A between IMI and HSA at three differences were obtained to be 1.51×104, 1.58×104, and 2.19×104 Lmol−1, respectively. The thermodynamic parameters, ΔH° and ΔS° were estimated to be 28.44kJmol−1, 174.76Jmol−1 K−1 according to the van’t Hoff equation. Hydrophobic interactions played a major role in stabilizing the complex. The distance r between donor (HSA) and acceptor (IMI) was obtained according to fluorescence resonance energy transfer. The effect of IMI on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy CD and three-dimensional fluorescence spectra, the environment around Trp and Tyr residues were altered. [Copyright &y& Elsevier]

Abstract: Tris(dibenzoylmethanate)(phenanthroline)europium(III)[Eu(DBM)3Phen]-doped amphiphilic vesicles were obtained by self-assembling of poly(N-isopropylacrylamide)-b-poly{6-[4-(4-methylphenyl-azo) phenoxy] hexylacrylate} (PNIPAM83-b-PAzoM20) in presence of Eu(DBM)3Phen in the mixed solvent of THF/H2O (50/50 vol.%). Their optical properties were studied by UV–vis and fluorescence spectroscopies. The UV–vis spectrum showed that the electronic transition bands of azobenzene and Eu(DBM)3Phen were overlapped at about 365nm and the main peak of fluorescence emission band appeared at 612nm. So the vesicles showed obvious red luminescence. It was found that the fluorescence intensity of a single Eu(DBM)3Phen-doped vesicle could be modulated by irradiation with UV and visible light due to the reversible trans–cis–trans photoisomerization reaction of azobenzene moiety. Possible energy allocation process for this property was discussed in details. [Copyright &y& Elsevier]

Abstract: The interaction between bovine hemoglobin (BHb) and TiO2 colloid was investigated by UV/vis absorption, UV/vis diffuse reflectance spectrum, IR, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. TiO2 effectively quenched the intrinsic fluorescence of BHb via static quenching. The process of binding TiO2 on BHb was a spontaneous molecular interaction procedure. The thermodynamic parameters, ΔH° and ΔS° were estimated to be −78.07kJmol−1, −110.93Jmol−1 K−1 according to the van’ Hoff equation. This indicates that the van der Waals and hydrogen bonds interactions played a major role in stabilizing the TiO2–BHb complex. The effect of TiO2 on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy. [Copyright &y& Elsevier]

Abstract: The interaction of benzidinne (BZ) with bovine hemoglobin (BHb) under physilolgical condition was studied by fluorescence spectrum. Fluorescence data revealed that the fluorescence quenching of BHb by BZ was the result of the formed complex of BZ–BHb, The quenching and energy transfer mechanisms were discussed, respectively. The binding constants and thermodynamic parameters at three different temperatures, the binding locality, and the binding power were obtained. The hydrophobic and hydrogen bonds interactions were the predominant intermolecular forces to stabilize the complex. The conformation of BHb was discussed by synchronous and three-dimensional fluorescence techniques. [Copyright &y& Elsevier]

Abstract: The interaction between the flavonoid hesperidin and bovine serum albumin (BSA) was investigated by fluorescence and UV/Vis absorption spectroscopy. The results revealed that hesperidin caused the fluorescence quenching of BSA through a static quenching procedure. The hydrophobic and electrostatic interactions play a major role in stabilizing the complex. The binding site number n, and apparent binding constant K A, corresponding thermodynamic parameters ΔG o, ΔH o, ΔS o at different temperatures were calculated. The distance r between donor (BSA) and acceptor (hesperidin) was obtained according to fluorescence resonance energy transfer. The effect of Cu2+, Zn2+, Ni2+, Co2+, and Mn2+ on the binding constants between hesperidin and BSA were studied. The effect of hesperidin on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy and UV/Vis absorption spectroscopy. [Copyright &y& Elsevier]

Abstract: The interaction between paraquat (PQ) and bovine hemoglobin (BHb) was investigated using fluorescence and UV/vis absorption spectroscopy. The reactivity of the heme centers with superoxide anions formed by PQ was judged on the basis of the decrease of the Soret band. The experimental results showed that the fluorescence quenching of BHb by PQ was a result of the formation of PQ–BHb complex; static quenching was confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K A and corresponding thermodynamic parameters were measured at different temperatures. The process of binding PQ molecule on BHb was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The effect of PQ on the conformation of BHb was analyzed using synchronous fluorescence spectroscopy. [Copyright &y& Elsevier]

Abstract: The interaction between silicotungstic acid and bovine serum albumin (BSA) was investigated using fluorescence and UV/vis. The experimental results showed that the fluorescence quenching of BSA by silicotungstic acid is a result of the formation of SiW–BSA complex; static quenching and non-radiative energy transferring were confirmed to result in the fluorescence quenching. The binding site number n, apparent binding constant K A and corresponding thermodynamic parameters were measured at different temperatures. The process of binding SiW molecule on BSA was a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic interaction force plays a major role in stabilizing the complex. The effect of silicotungstic acid on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. [Copyright &y& Elsevier]

Abstract: The interaction between palmatine hydrochloride with human serum albumin (HSA) was investigated by fluorescence quenching technique and UV/vis absorption spectroscopy. The results of fluorescence titration revealed that palmatine hydrochloride could strongly quench the intrinsic fluorescence of HSA by static quenching and nonradiative energy transferring. The electrostatic interaction plays a major role in stabilizing the complex. The binding site number n and apparent binding constant K A, corresponding thermodynamic parameters ΔG, ΔH and ΔS at different temperatures were calculated. The distance r between donor (HSA) and acceptor (palmatine hydrochloride) was obtained according to fluorescence resonance energy transfer. The effect of palmatine hydrochloride on the conformation of HSA was analyzed using synchronous fluorescence spectroscopy. [Copyright &y& Elsevier]

Abstract: The interaction between Cr2O7 2− and human serum albumin (HSA) was investigated using fluorescence, UV/vis, FT-IR, CD spectroscopy, and molecular modeling method. The experimental results showed that the fluorescence quenching of HSA by Cr2O7 2− is a result of the formation of HSA–chromium(VI) complex; static quenching was confirmed to result in the fluorescence quenching. The corresponding thermodynamic parameters showed that the process of binding Cr2O7 2− on HSA was a spontaneous molecular interaction procedure. Ionic, H-bonds and van der Waals interactions play a major role in stabilizing the complex. The Cr2O7 2− altered the environments of Trp and Tyr residues in HSA. [Copyright &y& Elsevier]

The interactions of 2, 4-dinitrophenol and 2, 4-dichlorphenol with trypsin were investigated by fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. The 2, 4-dinitrophenol and 2, 4-dichlorphenol effectively quenched the intrinsic fluorescence of trypsin via static quenching. The process of binding 2, 4-dinitrophenol and 2, 4-dichlorphenol with trypsin was a spontaneous molecular interaction procedure. The electrostatic repulsion does favor the interaction between 2, 4-DNP and trypsin. However, the interaction of 2, 4-DCP and trypsin can be explained on the basis of hydrogen bonding and van der Waals. The results of synchronous fluorescence spectroscopy and three-dimensional fluorescence spectra indicated that the structure of these trytophan and tyrosine residues environments were altered by 2, 4-DNP and 2, 4-DCP. [ABSTRACT FROM AUTHOR]

In this report, the binding interaction of chromium(VI), as Cr 2 O 7 2− , with humic acid was studied by using UV–visible absorption, fluorescence spectroscopy, and molecular modeling method. The fluorescence spectral data indicated that the binding interaction existed between Cr 2 O 7 2− and humic acid and the order of magnitude of binding constants were 10 3 . The rise in temperature caused a decrease in the values of the binding constant of humic acid with Cr 2 O 7 2− . Thermodynamic analysis presented that multi-intermolecular forces including hydrogen bonding, hydrophobic, and electrostatic forces were involved in the binding process at pH 6.5. The spectral data also indicated that Cr 2 O 7 2− affected the aromatic ring structures in humic acid. Furthermore, the molecular modeling analysis indicated that a lot of reactive groups and binding cavities in HA played a key role in its binding with Cr 2 O 7 2− . [ABSTRACT FROM AUTHOR]

A series of 2- and 2,4-substituted 5-cyanopyrazolo[1,5- a ]pyridine derivatives were conveniently synthesized by a one-pot tandem reaction under mild conditions in moderate yields. The reaction mechanism was also proposed. Some of the 2,4-substituted pyrazolo[1,5- a ]pyridines display blue fluorescence not only in dilute solution but also in the solid state. [ABSTRACT FROM AUTHOR]

Abstract: The interaction between triphenyltin (TPT) and humic acid (HA) was investigated using UV–vis and fluorescence spectra techniques. The experimental results showed that the fluorescence quenching of HA by TPT was a result of the interaction of TPT with HA. The binding constant K b and corresponding thermodynamic parameters were measured at different temperatures. The binding of TPT molecule to HA is a spontaneous molecular interaction procedure in which entropy increased and Gibbs free energy decreased. Hydrophobic interaction force plays a major role in stabilizing the TPT–HA complex. The three-dimensional fluorescence contour spectra revealed that TPT could enter into the hydrophobic cavities in some domain of HA. [Copyright &y& Elsevier]

Abstract: The interaction between lysozyme and cinnamic acid was investigated systematically by ultraviolet–vis absorbance, circular dichroism, fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques at pH 7.40. The binding constants, quenching mechanism, and the number of binding sites were determined by the quenching of lysozyme fluorescence in presence of cinnamic acid. The results showed that the fluorescence quenching of lysozyme by cinnamic acid was a result of the formation of cinnamic acid–lysozyme complex. The hydrophobic and electrostatic interactions played major roles in stabilizing the complex; the distance r between donor and acceptor was obtained to be 2.07nm according to Förster’s theory; the effect of cinnamic acid on the conformation of lysozyme was analyzed using synchronous fluorescence, circular dichroism and three-dimensional fluorescence spectra. [Copyright &y& Elsevier]

The interactions between Al(III)-tetracarboxyphthalocyanine (AlPc(COOH)4) and hemoglobin (or myoglobin) have been studied. The results showed that AlPc(COOH)4 effectively quenched the intrinsic fluorescence of Hb and Mb via static quenching. The hydrophobic and electrostatic interactions played a major role in stabilizing the AlPc(COOH)4-protein complex. The distance r between donor and acceptor was obtained to be 3.92 and 3.67 nm for AlPc(COOH)4-Hb and AlPc(COOH)4-Mb system, respectively. The effect of AlPc(COOH)4 on the conformation of Hb and Mb was analyzed using UV–vis absorption spectroscopy, circular dichroism spectra, synchronous fluorescence and three-dimensional fluorescence spectra. [ABSTRACT FROM AUTHOR]

The interactions between rutin and trypsin were investigated by UV-Vis absorption, CD, fluorescence, resonance light-scattering spectra, synchronous fluorescence, and three-dimensional fluorescence spectra techniques under physiological pH 7.40. Rutin effectively quenched the intrinsic fluorescence of trypsin via static quenching. The enthalpy change and entropy change were estimated to be -8.23 kJ·mol-1 and 53.66 J·mol-1·K-1 according to the van't Hoff equation. The process of binding rutin to trypsin was a spontaneous molecular interaction procedure. This result indicates that hydrophobic and electrostatic interactions played a major role in stabilizing the complex. The conformation of trypsin was discussed by CD, synchronous, and three-dimensional fluorescence techniques. [ABSTRACT FROM AUTHOR]

Abstract: The interaction between three purine alkaloids (caffeine, theophylline, and theobromine) and human serum albumin (HSA) was investigated using UV/vis absorption, circular dichroism (CD), fluorescence, synchronous fluorescence, and three-dimensional fluorescence spectra techniques. The results revealed that three alkaloids caused the fluorescence quenching of HSA by the formation of alkaloid–HSA complex. The binding site number n and apparent binding constant K A, corresponding thermodynamic parameters the free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS) at different temperatures were calculated. The hydrophobic interaction plays a major role in stabilizing the complex. The distance r between donor (HSA) and acceptor (alkaloids) was obtained according to fluorescence resonance energy transfer. The effect of alkaloids on the conformation of HSA was analyzed using circular dichroism (CD), UV/vis absorption, synchronous fluorescence and three-dimensional fluorescence spectra techniques. [Copyright &y& Elsevier]

Abstract: Eu(DBM)32H2O and Eu2(DDBM)3H2O were synthesized by reactions between EuCl3 and chelating regents of β-diketone (dibenzoylmethane, HDBM) and bis(β-diketone) (1,3-bis(3-phenyl-3-oxopropanoyl)benzene, H2DDBM), respectively, and their luminescence properties were investigated by the fluorescence spectra and metastable state decay spectra. It was found that the relative intensity ratio of 5D0→7F2 to 5D0→7F1transition and the radiative lifetime shows a little change attributing to the different symmetry of europium ions, which Ω 2 of Eu complexes with β-diketone and bis(β-diketone) are 13.08 and 12.24, respectively. Moreover, it was also found that the metastable state lifetime of Eu2(DDBM)3H2O is much longer than that of Eu(DBM)32H2O, due to smaller water quenching and lower triplet level of ligands. The Commission Internacionale d’Éclairage (CIE) chromaticity coordinates calculated from emission spectrum are x=0.637 and y=0.343 for Eu2(DDBM)3H2O, which presents high red color purity near 100%. [Copyright &y& Elsevier]