Search

The detection and discrimination of Fe2+ and Fe3+ ions have been investigated using a simple probe (L), produced by the condensation of ethylenediamine and 3-ethoxysalicyaldehyde. Single crystal X-ray structures demonstrate that L interacts with Fe2+ and Fe3+. In aqueous-DMSO media, the L recognises AsO2− by fluorescence and colorimetry techniques. The AsO2− aided PET inhibition and H-bond assisted chelation enhanced fluorescence (CHEF) boost fluorescence by 91-fold. The L can detect 0.354 ppb Fe2+, 0.22 ppb Fe3+ and 0.235 ppt AsO2−. [ABSTRACT FROM AUTHOR]

The detection and discrimination of Fe2+ and Fe3+ ions have been investigated using a simple probe (L), produced by the condensation of ethylenediamine and 3-ethoxysalicyaldehyde. Single crystal X-ray structures demonstrate that L interacts with Fe2+ and Fe3+. In aqueous-DMSO media, the L recognises AsO2− by fluorescence and colorimetry techniques. The AsO2− aided PET inhibition and H-bond assisted chelation enhanced fluorescence (CHEF) boost fluorescence by 91-fold. The L can detect 0.354 ppb Fe2+, 0.22 ppb Fe3+ and 0.235 ppt AsO2−. [ABSTRACT FROM AUTHOR]

An unsymmetrical bis‐imine derivative (A2) selectively detect Al3+, Zn2+ and OCl− in a solvent dependent manner where Al3+ and Zn2+ emit green and blue light in DMSO−H2O media while OCl− emits green‐yellow light in aqueous ethanol. The corresponding florescence enhancements are 8.2 fold, 3.7 fold (chelation enhanced fluorescence and excited state intra‐molecular proton transfer OFF) and 10.6 fold (H‐bonding, excited state intra‐molecular proton transfer OFF) respectively. While the limit of detection (LODs) for Al3+, Zn2+ and OCl− are 49 nM, 35 nM and 74 nM respectively, the corresponding binding/ association constants are 1.79×105 M−1, 1.8×105 M−1 and 3.68×105 M−2. The results of density functional theory (DFT) studies are fairly close to that of experimental findings. [ABSTRACT FROM AUTHOR]

An amide‐imine conjugate, (E)‐N′‐((2‐hydroxybenzen‐1‐yl) methylene)‐4‐methylbenzohydrazide (H2LPTASAL), derived from 4‐methyl‐benzoic acid hydrazide (PTA) and 2‐hydroxybenzaldehyde is used to prepare Mo (VI), Cu (II) and Fe (III) complexes. The X‐ray structurally characterized complexes have been explored as catalyst for amine assisted asymmetric ring opening (ARO) of epoxide, carbon‐heteroatom cross‐coupling and ethyl benzene oxidation. In addition, their catecholase like activities have thoroughly been investigated. Moreover, the Cu (II) complex selectively recognizes histidine by fluorescence spectroscopy. [ABSTRACT FROM AUTHOR]

Single crystal X-ray structurally characterized azo-uracil derivative (L) is explored for the selective detection of pyrene via aggregation-induced emission (AIE) with 99-fold fluorescence enhancement. In the presence of pyrene, non-fluorescent L emits green light and allows pyrene detection to as low as 3.6 × 10−9 M. Three model probes (L1, L2 and L3) were employed to support the proposed sensing mechanism. Further, silica-immobilized L efficiently removes pyrene from its reservoir. [ABSTRACT FROM AUTHOR]

A single crystal X-ray structurally characterized amide–imine conjugate (GAN) derived from gallic acid and naphthalene selectively recognizes La3+ ions via TURN ON fluorescence through ESIPT and CHEF mechanisms. GAN can detect as low as 23.93 × 10−9 M La3+ ions and image intracellular La3+ ions in live HeLa and SiHa cells under a fluorescence microscope in a time- and concentration dependent manner. The corresponding [La(III)–GAN] complex is established as an efficient catalyst for the synthesis of benzimidazole derivatives from o-phenylenediamine and substituted benzaldehydes. Moreover, GAN is very useful for enrichment of La3+ in ethyl acetate medium. [ABSTRACT FROM AUTHOR]

The oxo‐vanadium(V) complex (1) derived from an amide‐imine conjugate, (E)‐N′‐(4‐(diethylamino)‐2‐hydroxybenzylidene)‐2‐(naphthalen‐1‐yl)acetohydrazide (H2L1) is exploited as catalyst for arresting atmospheric CO2 to organic cyclic carbonate by reacting with epoxide. The H2L1 is prepared by facile condensation of 2‐(naphthalen‐1‐yl)acetohydrazide (AC) and 4‐(diethylamino)‐2‐hydroxybenzaldehyde in good yield. The 1 is characterized by single crystal X‐ray diffraction, FTIR and absorption spectroscopic studies. [ABSTRACT FROM AUTHOR]

• Report on discrimination of group 12 metal ions using a rhodamine derived smart optical probe (L). • The L detects as low as 1.2 × 10−9 M Zn2+, 9.6 × 10−9 M Cd2+ and 1.5 × 10-10 M Hg2+. • L determines Cd2+ and Hg2+ in sea fishes. • Binary logic gate has been constructed. • TD-DFT studies support experimental spectral properties of L and its cation adduct. A multi-signaling optical probe (L) having rhodamine B spacer has been developed for rapid detection and discrimination of Zn2+, Cd2+ and Hg2+ at nano-molar level. L recognizes them through bare eye, absorption and emission spectroscopy. The probe detects as low as 1.2 × 10−9 M Zn2+, 9.6×10−9 M Cd2+ and 1.5×10-10 M Hg2+ with corresponding binding constants, 2.1 × 104 M-1, 6.5 ×105 M−1 and 3.4×106 M−1 respectively. The recognition mechanism involves PET-CHEF-FRET processes. TD-DFT studies reveal minimum energy optimized geometries of L and its' adduct with the said cations. Theoretical calculations also support experimental spectral properties. Interference free new method allows determination of said cations in sea fish and water samples. [ABSTRACT FROM AUTHOR]

Single crystal X-ray structure-characterized azine derivative (L) was explored for the selective detection of molybdenum (Mo(vi)) cations through green fluorescence emission. The Mo(vi) cation assisted inhibition of photo-induced electron transfer (PET) resulted in a 37-fold fluorescence enhancement via chelation enhanced fluorescence (CHEF) that allows detection of Mo(vi) with concentration as low as 2 × 10−9 M. The chelation of Mo(vi) cations by L has been confirmed by the single crystal X-ray structure of the resulting complex. The binding constant of L for Mo(vi) is fairly high (1.33 × 106 M−1). Moreover, L is very efficient for enrichment of Mo(vi) from aqueous solution. Density functional theoretical (DFT) studies substantiate the experimental results. [ABSTRACT FROM AUTHOR]

Bringing o - aminothiophenol, salisaldehyde and rhodamine-B under an umbrella to link them chemically, an excellent probe ( L ) is designed, prepared and characterised to detect and discriminate Hg 2+ and Al 3+ using emission and absorption spectroscopy. In presence of Hg 2+ , L emits bright red color. The same color is observed in bare eye in visible light. On the other hand, Al 3+ imparts green and pink colors under similar conditions. UV–vis and fluorescence titration, 1 H NMR and fluorescence lifetime decay studies unveil the recognition event. Live cell imaging, sea fish and environmental sample analysis has also been performed. [ABSTRACT FROM AUTHOR]

Tuning of ligand structures through controlled variation of ring number in fused‐ring aromatic moiety appended to antipyrine allows detection of 7.8 × 10−12 M pyrene via aggregation‐induced emission (AIE) associated with 101‐fold fluorescence enhancement. In one case, antipyrine unit is replaced by pyridine to derive bis‐methylanthracenyl picolyl amine. The structures of four molecules have been confirmed by single crystal X‐ray diffraction analysis. Among them, pyrene‐antipyrine conjugate (L) undergoes pyrene triggered inhibition of photo‐induced electron transfer (PET) leading to water‐assisted AIE. An antipyrine‐pyrene conjugate (L) detects picomolar (7.8 × 10−12 M) pyrene in aqueous‐DMSO media through generation of green fluorescence via water‐assisted aggregation‐induced emission (AIE) mechanism. The association constant, Ka is 3.81 × 106 M−1. L efficiently detects intracellular pyrene through fluorescence microscope and determines concentration of pyrene of Gomti river water. L‐immobilized silica efficiently removes pyrene from real samples by SPE. [ABSTRACT FROM AUTHOR]

An anthracene based unsymmetrical azine derivative, viz. 4-(anthracen-9-ylmethylene-hydrazonomethyl)-2-methoxy-phenol (L5), is synthesized and structurally characterized by single crystal X-ray diffraction (SC-XRD) analysis. The photo-physical interaction of L5 with Al3+ in sodium dodecyl sulfate (SDS) is highly selective, allowing recognition of nanomolar (62.8 nM) Al3+ without interference from common cations. The Job plot shows a 1 : 1 (mole ratio) interaction with an associated binding constant of 9.14 × 104 M−1. The "turn ON" fluorescence is attributed to aggregation induced emission (AIE). The Al3+ assisted particle size enhancement of L5 from 52.70 nm to 3413.06 nm (3.413 μM) observed through DLS studies corroborates the AIE mechanism. FESEM images also support the proposed mechanism. The cylindrical morphology of L5 changes to a cube shape due to aggregation of the [Al3+ + L5] adduct. Fluorescence lifetime decay (TCSPC) data indicate that the radiative decay of L5 is enhanced about ten times in the presence of Al3+. The average lifetime of L5 in the absence and presence of Al3+ is 0.98 ns and 1.45 respectively. In the presence of Na2EDTA, the emission intensity of the [L5 + Al3+] system is significantly quenched due to chelation of Al3+ by EDTA. TDDFT studies indicate higher stability of the [L5 + Al3+] adduct over free L5. [ABSTRACT FROM AUTHOR]

Abstract Single crystal X-ray structurally characterized benzimidazole-naphthalene hybrid (NABI) functions as a unique dual analyte sensor that can detect Zn2+ cation and N 3 − anion independently. The NABI forms chelate with Zn2+ to inhibit internal charge transfer (ICT) and CH N isomerisation resulting chelation enhanced fluorescence (CHEF). On the other hand, the sensing of N 3 − is based on formation of supramolecular H-bonded rigid assembly. The association constant of NABI for Zn2+ and N 3 − ions are 19 × 104 M−1 and 11 × 102 M−1, respectively. Corresponding limit of detections (LOD) are 6.85 × 10−8 and 1.82 × 10−7 M, respectively. NABI efficiently detects intracellular Zn2+ and N 3 − ions with no cytotoxicity on J774A.1cells under fluorescence microscope. DFT studies unlock underlying spectroscopic properties of free NABI and Zn2+/N 3 − bound forms. Graphical Abstract A benzimidazole-naphthalene hybrid (NABI) acts as a dual analyte sensor and detects Zn2+ and N 3 − independently. The sensing of Zn2+ occurs through inhibition of internal charge transfer (ICT) and CH N isomerisation along with chelation enhanced fluorescence (CHEF) whereas N 3 − sensing proceeds through formation of supramolecular H-bonded rigid assembly. Single crystal X-ray structurally characterized NABI has association constant for Zn2+ and N 3 − ions, 19 × 104 M−1 and 11 × 102 M−1 respectively. Corresponding limit of detections (LOD) are 6.85 × 10−8 and 1.82 × 10−7 M. NABI efficiently detects intracellular Zn2+ and N 3 − ions with no cytotoxicity on J774A.1cells under fluorescence microscope. DFT studies unlock underlying spectroscopic properties of free NABI and its Zn2+/N 3 − bound forms. Unlabelled Image Highlights • A benzimidazole–naphthalene (NABI) fluorescence probe selectively and independently detects Zn2+ and N 3 − ions. • The CHEF assisted Zn2+ sensing involves inhibition of ICT and CH N isomerization while N 3 − sensing proceeds through supramolecular H-bond assisted rigid structure formation. • The association constants of NABI for Zn2+ and N 3 − ions are 19 × 104 M−1 and 11 × 102 M−1 while corresponding LODs are 6.85 × 10−8 and 1.82 × 10−7 M. • X-ray structurally characterized, non- cytotoxic NABI efficiently detects Zn2+ and N 3 − ions within J774A.1cells. • DFT studies unfold underlying spectroscopic properties of free NABI and its Zn2+ and N 3 − adducts. [ABSTRACT FROM AUTHOR]

4-Hydroxy-5-isopropyl-2-methylisophthalaldehyde anchored rhodamine B derivative, RDDFT experiences Fe 3+ assisted inhibition of photoinduced electron transfer (PET), chelation-enhanced fluorescence (CHEF) and fluorescence resonance energy transfer (FRET) process in aqueous buffered acetonitrile media. RDDFT is an excellent colorimetric Fe 3+ probe that undergoes ratiometric fluorescence change to recognize and determine traces of Fe 3+ in presence of Fe 2+ in real sample, thus allowing speciation studies of iron. It detects as low as 2 × 10 −8 M Fe 3+ with an association constant, 3.7025 × 106 M −1 . Common ions do not show any significant interference in the detection of Fe 3+ ion. RDDFT efficiently images intracellular Fe 3+ in HeLa cells under fluorescence microscope. DFT studies strongly support experimental findings. [ABSTRACT FROM AUTHOR]

Combination of pyridine, antipyrine and indole in a single molecule ( L2 ) allows selective recognition of Fe 3 + colorimetrically in CH 3 CN. The structure of L2 is confirmed from single crystal X-ray diffraction analysis. The probe displays two different visible bands at 541 nm and 715 nm in the presence of Fe 3 + , associated with two different colors, viz. green and pink-violet allowing determination of unknown Fe 3 + concentration. Interestingly, removal of 2-picolyl group from indole N-center of L2 generates L3 that behaves similarly at low Fe 3 + concentration (> 0 to 1.1 mM) but differently at higher Fe 3 + concentration (> 1.1 mM), indicating involvement of pyridyl-N donor towards Fe 3 + , and hence different coordination environment around Fe 3 + at higher concentration. [ABSTRACT FROM AUTHOR]

Several naphthalene-based aldazine derivatives were developed as efficient colorimetric and fluorescence probes for selective ratiometric recognition of traces of zinc acetate. The derivative structures were characterized by single-crystal X-ray diffraction. The probes were used for in vitro tracking of zinc acetate in endophytic bacteria within rice root tissue and to image zinc acetate in human breast cancer cells (MCF7) by normal and fluorescence microscopy. Density functional theoretical studies were in close agreement with the experimental findings. [ABSTRACT FROM AUTHOR]

Fluorescence recognition of Zn in 100 % aqueous medium using 2-((1, 3 dihydroxy-2-(hydroxymethyl)propan-2 ylimino) methyl) phenol (SALTM) as ratiometric probe is reported. Moreover, SALTM can discriminate Zn from Cd very effectively. The binding constant and detection limit of the probe for Zn is 2.2 × 10 M and 2.79 × 10 M respectively. Interestingly, corresponding naphthalene derivative (HNTM) having less water solubility fails to be a ratiometric sensor. SALTM can detect intracellular Zn in HeLa cervical cancer cells under fluorescence microscope. Moreover, DFT and TD-DFT studies support experimental findings. [ABSTRACT FROM AUTHOR]

A new amide–imine conjugate, 2-hydroxybenzoic acid-(2-hydroxybenzylidene)-hydrazide (L1), is employed to prepare a single crystal X-ray structurally characterized poly-nuclear Cu(II) complex (M1). M1 selectively and spatially interacts with cytochrome C (Cyt C) to allow fluorescence imaging of intracellular translocation events in living cells. Thus, direct visualization of a Cyt C translocation event during an apoptotic process is achieved for the first time. The binding constant and LOD are 7.52 × 104 M−1 and 34.0 nM, respectively. [ABSTRACT FROM AUTHOR]