A new coumarin based Schiff-base chemosensor-(E)-7-(((8-hydroxyquinolin-2-yl)methylene) amino)-4-methyl-2H-chromen-2-one (H11L) was synthesized and evaluated as a colorimetric sensor for Fe3+ and fluorescence “turn on-off” response of Zn2+ and Cu2+ using absorption and fluorescence spectroscopy. Upon treatment with Fe3+ and Zn2+, the absorption intensity as well as the fluorescence emission intensity increases drastically compared to other common alkali, alkaline earth and transition metal ions, with a distinct color change which provide naked eye detection. Formation of 1:1 metal to ligand complex has been evaluated using Benesi-Hildebrand relation, Job’s plot analyses, 1H NMR titration as well as ESI-Mass spectral analysis. The complex solution of H11L with Zn2+ ion exhibited reversibility with EDTA and regenerate free ligand for further Zn2+ sensing. H11L exhibits two INHIBIT logic gates with two different chemical inputs (i) Zn2+ (IN1) and Cu2+ (IN2) and (ii) Zn2+ (IN1) and EDTA (IN2) and the emission as output. Again, an IMPLICATION logic gate is obtained with Cu2+ and EDTA as chemical inputs and emission as output mode. Both free ligand as well as metal-complexes was optimized using density functional theory to interpret spectral properties. The corresponding energy difference between HOMO-LUMO energy gap for H11L, H11L-Zn2+ and H11L-Cu2+ are 2.193, 1.834 and 0.172 eV, respectively. 相似文献
A highly selective and sensitive fluorescent Zn2+ sensor N-(2-(benzo[d]thiazol-2-yl)phenyl)-2-((pyridin-2-ylmethyl)amino)acetamide (1) that derived from 2-(2′-aminophenyl)benzothiazole has been developed. In aqueous solution (HEPES/CH3CN=4/6, v/v, HEPES 20 mM, pH?=?7.4), sensor 1 displays highly selective recognition to Zn2+ over other metal ions with a distinct longer-wavelength emission enhancement. Sensor 1 binds Zn2+ through its amide form with a 1:1 binding stoichiometry, which switched on the excited-state intramolecular proton transfer (ESIPT). Graphical Abstract
A simple 2-(2′-aminophenyl)benzothiazole-based fluorescent “off-on” sensor for Zn2+ recognition in HEPES/CH3CN(4/6, v/v, HEPES 20 mM, pH?=?7.4) solution through switching on ESIPT has been developed.相似文献
Urea based fluorescent chemosensor 1 was synthesized. Receptor 1 shows unique selectivity for the Fe3+ion and no such significant response was noticed with other metal ions (Cr3+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ and Bi3+) in DMSO/H2O (50:50,v/v) semi-aqueous solution. The binding features have been established by absorption and fluorescence spectroscopic methods. The binding constant (K) values obtained from Benesi-Hildebrand, Scatchard and Connor plot for receptor 1 is (8.3?±?0.3) × 103 M?1 and has good detection limit 0.7?μM. The stoichiometry of 1.Fe3+ complex was confirmed by mass spectroscopy and Job’s plot.
Imbalance of zinc ion (Zn2+) in human body causes diseases like Alzheimer’s and Parkinson’s and therefore Zn2+ estimation in biological fluids has diagnostic values. Fluorescence “off-on” sensors have advantages of high sensitivity and in situ application over other sensors. A new fluorescent “off-on” Zn2+ sensor, N-benzoate-N′ salicylaldehyde ethynelediamine (L), has been synthesisied. In 1:1(v/v) CH3OH:PBS (PBS?=?phosphate buffer solution), L shows ca. 20 times enhancement in fluorescence intensity on interaction with Zn2+, due to snapping of photoinduced electron transfer (PET) process, which is selective over metal ions - Na+, K+, Ca2+, Ni2+, Cu2+, Cd2+, Hg2+ and Pb2+. These metal ions either individually or all together does not interfere the sensing ability of L towards Zn2+. A 1:1 interaction between L and Zn2+ ion with binding constant 104.25 has been established from spectroscopic data. 相似文献
In this work, the dipod 9,10-bis(8-quinolinoxymethyl)anthracene (1) and for comparison, monopod 9-(8-quinolinoxymethyl)anthracene (2) have been synthesized. The fluoroionophore 1 in pH 7.1 HEPES buffered CH3CN:H2O (4:1 v/v) solution shows quenching only with Cu2+ with lowest limit of detection 150 nM, amongst various metal ions. Fluoroionophore 1 could also be applied to sense Co2+ with lowest limit of detection 600 nM. By modulating the pH of the solution and concentration of Cu2+, 1 shows respective “On-Off-On” and “On-Off” fluorescent switching. The self-assembly of two Cu2+ ions and two molecules of fluoroionophore 1 to form closed structure [Cu2(L)2]4+ seems to be responsible for nanomolar sensitivity towards Cu2+. The combination of delayed second protonation of 1 (pKa2?=?2.6) and stepwise protonation of [Cu2L2]4+ causes unusual stability of [Cu(LH)2]4+ even at pH?<?2.
Figure
The fluoroionophore 1 shows quenching only with Cu2+ with lowest limit of detection 150 nM. The combination of delayed second protonation of 1 (pKa2?=?2.6) and stepwise protonation of [Cu2L2]4+ causes unusual stability of [Cu(LH)2]4+ even at pH?<?2. 相似文献
A novel series colorimetric and off–on fluorescent chemosensors (2a, 2b, 2c) were designed and synthesized, which showed reversible and highly selective and sensitive recognition toward Fe3+ over other examined metal ions. Upon addition of Fe3+, sensors (2a, 2b) exhibit remarkably and 2c exhibits moderate enhanced absorbance intensity and color change from colorless to pink in CH3OH–H2O(1:1, v/v). The three compounds (2a, 2b, 2c) may therefore be applicable as rhodamine-based turn-on type fluorescent chemosensors. 相似文献
An efficient “off–on” type fluorescent chemosensor, (E)-N′-(4-(diethylamino)-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H2L), based on Schiff base for the determination of Al3+ has been designed, synthesized, and evaluated. Upon treated with Al3+, the fluorescence of H2L was enhanced 45-fold due to the chelation-enhanced fluorescence (CHEF) effect based on the formation of a 1:1 complex between the chemosensor and Al3+. Other metal ions, such as Na+, K+, Mg2+, Ca2+, Cu2+, Ga3+, Zn2+, Cr3+, Cd2+, Ag+, Fe3+, In3+, Mn2+, Pb2+, Co2+, and Ni2+ had little effect on the fluorescence. The results demonstrate that the chemosensor H2L has stronger affinity with Al3+ than other metal ions. The detection limit of H2L for sensing Al3+ is 3.60 × 10?6 M in EtOH–H2O (3:7, v/v) solution. And the recognizing behavior has been investigated both experimentally and computationally. 相似文献
A new fluorescent probe based on a bis-benzimidazole diamide N2,N2′-bis[(1-ethyl-benzimidazol-2-yl)methyl]biphenyl-2,2′-dicarboxamide ligand L1 with a biphenyl spacer group and a Copper(II) trinuclear metallacycle has been synthesized and characterized by X-ray single crystallography, elemental and spectral (FT-IR, 1H & 13C NMR, UV-Visible) analysis. The fluorescence spectra of L1 in MeOH show an emission band centered at 300 nm. This band arises due to benzimidazolyl moiety in the ligating system. The diamide L1 in the presence of Cu2+ show the simultaneous ‘quenching’ of (300 nm) and ‘enhancement’ of (375 nm) emission band. Similar fluorescence behavior was found in water–methanol mixture (9:1). The new emission band at 375 nm is attributed to intra ligand π–π* transition of the biphenyl moiety. L1 exhibited high selectivity and sensitivity towards Cu2+ in both the medium over other common metal ions like Ni2+, Co2+, Mn2+, Mg2+, Zn2+, Pb2+ and Hg2+. The binding constant with Cu2+ was calculated by the Benesi-Hildebrand equation. Selective “off-on-off” behavior of L1 in methanol has also been studied. The fluorescent intensity of 375 nm bands in L1 enhances (turns-on) upon addition of Cu2+ and quenches (turn-off) upon addition of Na2-EDTA. 相似文献
The fluorescence intensity of salicylaldehyde phenylhydrazone (L), in 1:1 (v/v) CH3OH:H2O was enhanced by ca. 100 times with a blue shift in emission maximum, on interaction with Pb2+ ion. No enhancement in fluorescent intensity of L was observed on interaction with metal ions - Na+, K+, Ca2+, Cu2+, Ni2+, Zn2+, Cd2+ and Hg2+. This signal transduction was found to occur via photoinduced electron transfer (PET) mechanism. A 1:1 complexation between Pb2+ and L with log β?=?7.86 has been proved from fluorescent and UV/Visible spectroscopic data. The detection limit of Pb2+ was calculated to be 6.3?×?10?7?M. 相似文献
A series of indole-based fluorescent chemosensors 1–4 were prepared and investigated characteristick features with transition metal ions. Sensors 1 and 2 were selective for Hg2+ ion among a series of metal ions in H2O–DMSO with association constants of 4.60×104 and 5.90×104?M?1 and detection limits of 140 and 101.6 μM, respectively.
Figure
Indole-Based Fluorescent Sensors for Selective Detection of Hg2+. 相似文献
Novel substituted phenol-based new symmetrical bis(2-hydroxy-3-isopropyl-6-methyl-benzaldehyde)ethylenediamine (1) has been designed and synthesized. The compound 1 fluorometrically recognized Cu2+ ion in CH3OH/H2O (90:10, v/v) by exhibiting an increase in emission upon complexation. In addition, Cu2+ gave rise to a change in colour of the solution of compound 1, which was clearly visible to the naked eye under UV irradiation. The association constant (K) of compound 1 with Cu2+ ion was computed with the Benesi-Hildebrand plot and Scatchard plot at 43,000 M?1 and 43,011 M?1 respectively. 相似文献
With a new bis-azole molecular fragment (Htt) bearing 1,2,4-triazole and tetrazole, a mononuclear complex [Fe(tt)2(H2O)4]·2H2O (1), a trinuclear complex [Fe3(tt)6(H2O)6]·2H2O (2) and a 1D coordination polymer [Fe(tt)(Htt)2]BF4·2CH3OH (3) were obtained by varying reaction conditions. Htt acts either as an anionic or neutral ligand depending upon the reaction medium and pH. Thermal variation of spin states of 1–3 were investigated in the range 77–300?K by 57Fe M?ssbauer spectroscopy. 1 totally remains in high-spin state over the entire temperature range whereas no spin crossover was evidenced in 2. Nearly 1:1 high-spin and low-spin population ratio is found in 3, which remains constant over the entire temperature range investigated. 相似文献
‘Axial-bonding’-type hetero trimers have been constructed by employing a simple ‘inorganic’ reaction such as axial bond formation of main group element containing phosphorus corrole. The approach is simple and modular in nature. The architecture of these hetero trimers such that, while a phosphorus(V)corrole forms the basal scaffolding unit, either two free-base porphyrins [(H2)2–PCor] or ZnII porphyrins [(Zn)2–PCor] occupy the two axial sites via an aryloxy bridge. Both hetero trimeric species have been completely characterized by mass (FAB), UV/Vis, proton nuclear magnetic resonance spectroscopies and also by the differential pulse voltammetric method. Comparison of their spectroscopic and electrochemical data of these trimers with those of the corresponding reference compounds reveal that there is no apparent ring-to-ring interactions in these ‘vertically’ linked hetero trimers. Reduced fluorescence quantum yields were observed for [(H2)2–PCor] and [(Zn)2–PCor] when compared to corresponding monomeric chromophores. Finally, a comparison is made between the presently reported phosphorus(V)corrole based hetero arrays and the previously reported analogous arrays based on Ge(IV)corrole with regard to their spectroscopic properties and photochemical activities. 相似文献
Rhodamine B 8-hydroxy-2-quinolinecarboxaldehyde Schiff base (1) has been investigated as a colorimetric and fluorescent “off-on” probe for the recognition of Cu2+ in aqueous solution. Probe 1 was synthesized by condensation of rhodamine B hydrazide and 8-hydroxy-2-quinolinecarboxaldehyde, which exhibited good selectivity for Cu2+ among a range of biologically and environmentally important metal ions. The Cu2+ recognition event undergoes a Cu2+ promoted hydrolysis of probe 1 to release rhodamine B and the recognition process is barely interfered by other coexisting metal ions.
Figure
New application of Rhodamine B 8-hydroxy-2-quinolinecarboxaldehyde Schiff base as a colorimetric and fluorescent “off-on” probe for Cu2+ in CH3CN-H2O (1:1, v/v, HEPES 10 mM, pH?=?7.0) solution has been developed 相似文献
A pyridine based imine-linked chemosensor has been synthesized and evaluated its binding affinity with library of transition metal ions. It has prominent selectivity towards Pb2+ among other metal ions in DMF/H2O (9:1, v/v) solvent system. The 1:1 stoichiometric was confirmed by job’s plot and has a binding constant (Ka)?=?5.142?×?103 M?1 on fluorescence. A B3LYP/6-31G and B3LYP/LanL2DZ basis sets were employed for optimization of 3 and 3.Pb2+. 相似文献
Theoretical studies for a series of mono- and binuclear zinc (II) complexes Zn(CH3COO)2(H2L)2 [H2L = N-2-propenyl-N′-2-pyridinylthiourea] (A), Zn2(CH3COO)2(H3L-a)2 [H3L-a = 2-[(2-hydroxy phenyl)methylene]hydrazine-N-phenylcarbothioamide] (B), and Zn(H3L-b)2 [H3L-b = 2-[(2-hydroxy phenyl)methylene]hydrazine-N-(2-propenyl)carbothioamide] (C) have been performed on their structures and excited-state absorption spectra. The singlet ground-state geometries are fully optimised at three DFT levels, i.e., B3LYP, B3PW91, and M06. Different geometries, i.e., strongly distorted tetrahedral coordination environment in complex A, distorted square-pyramidal environment in complex B, and irregular octahedral mode in complex C are identified. Consequently, the spectroscopic properties are calculated by means of time-dependent density functional theory (TDDFT) with the Polarisable Continuum Model (PCM) based on the optimised gas-phase geometries. Three absorption peaks are identified for every complex, which are in good agreement with the experimental ones. For complex A, all three absorption peaks centered at 280.33 nm, 268.09 nm, and 250.87 nm, respectively, are ascribed to the (p,π) → π* transition with a mixed intraligand charge-transfer (ILCT)/ligand-ligand charge-transfer (LLCT) character. The composition of frontier orbitals involved in major absorption bands for the three complexes shows similarities, which results in the almost homologous transition attributions and characteristics. A remarkable bathochromic shift in the lowest-lying absorption band is observed for complexes B and C as compared with complex A, which is attributed to the decreased H (HOMO)-L (LUMO) energy gap (ΔE |HOMO-LUMO|) by the formation of conjugate metallocycles in complexes B and C. 相似文献
Selective fluorescence turn on Zn2+ sensor with long-wavelength emission and a large Stokes shift is highly desirable in Zn2+ sensing area. We reported herein the synthesis and Zn2+ recognition properties of a new thiosemicarbazone-based fluorescent sensor L. L displays high selectivity and sensitivity toward Zn2+ over other metal ions in DMSO-H2O (1:1, v/v, HEPES 10 mM, pH = 7.4) solution with a long-wavelength emission at 572 nm and a large Stokes shift of 222 nm. Confocal fluorescence microscopy experiments demonstrate that L is cell-permeable and capable of monitoring intracellular Zn2+.
Graphical Abstract We report a new thiosemicarbazone-based fluorescent sensor (L) for selective recognition of Zn2+ with a long wavelength emission and a large Stokes shift.
A new fluorescent probe for Mn2+ ion, (6E)-N-((E)-1,2-diphenyl-2-(pyridin-2-ylimino)ethylidene)pyridin-2-amine (L), has been synthesized from benzil and 2-amino pyridine and characterized. In 1:1 (v/v) CH3CN:H2O (pH 4.0, universal buffer) L exhibits fluorescent intensity with emission peak at λmax 360 nm on excitation with photons of 310 nm. Fluorescent intensity of L increases distinguishingly on interaction with Mn2+ ion compared to metal ions—Na+, K+, Ca2+, Mg2+, Ba2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ and Ag+ individually or all together. The enhancement in fluorescent intensity is due to snapping of photoinduced electron transfer (PET) prevailed in free L. Fluorescence and UV/visible spectral data analysis shows that binding stoichiometry between Mn2+ and L is 1:1 with log β?≈?3.0. Both L and its Mn2+ complex were optimised using density functional theory (DFT) and vibrational frequency calculations confirm that both are at local minima on the potential energy surfaces. 相似文献
The theory of spatial dispersion of dielectric and magnetic constants of magnetic uniaxial crystals based on generalized Maxwell’s equations D = ε?E = (ε + inγE = ?ns×H and B = μ?H = (μ + inδ)H = ns×E with spatial dispersion parameters γ and δ is considered. Generalized Fresnel’s and polarization equations for the obtained vectors E, D, H, and B are analyzed for the wave normal direction s ⊥ C (where C is the optic axis of a crystal). The possibility of the existence of a third natural wave in a crystal is proved. 相似文献
A new pyrene-based chemosensor (1) exhibits excellent selectivity for Fe3+ ions over a wide range of tested metal ions Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Pb2+, and Zn2+. The binding of Fe3+ to chemosensor 1 produces an emission band at 507 nm due to the formation of a Py-Py* excimer that is induced by Fe3+-binding. The binding ratio of 1-Fe3+ was determined to be 1:1 from a Job plot. The association constant of 1-Fe3+ complexes was found to be 1.27?×?104 M?1 from a Benesi-Hildebrand plot. In addition, fluorescence microscopy experiments show that 1 can be used as a fluorescent probe for detecting Fe3+ in living cells. 相似文献