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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]

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]

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]

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]

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]

Excited-state intra-molecular proton transfer (ESIPT)-active imine and azine derivatives, structurally characterised by XRD, and denoted L1, L2, L3 and L4, possess weak fluorescence. The interaction of these probes with Zn 2+ turns ON the fluorescence to allow its nano-molar detection. Among the four ESIPT-active molecules, L2, L3 and L4 are bis-imine derivatives while L1 is a mono-imine derivative. Among the three bis-imine derivatives, one is symmetric (L3) while L2 and L4 are unsymmetrical. The lowest detection limits (DL) of L1, L2, L3 and L4 for Zn 2+ are 32.66 nM, 36.16 nM, 15.20 nM and 33.50 nM respectively. All the probes bind Zn 2+ (10 5 M -1 order) strongly. Computational studies explore the orbital level interactions responsible for the associated photo-physical processes., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

An amide-based smart probe (L) is explored for nanomolar detection of Mo(VI) ion in a ratiometric manner, involving hydrogen-bond-assisted chelation-enhanced fluorescence process through inhibition of photoinduced electron transfer process. The recognition of Mo(VI) is associated with a 17-fold fluorescence enhancement and confirmed by single-crystal X-ray diffraction of the resulting Mo(VI) complex (M1). Further, M1 selectively recognizes arsenite through green emission of their adduct (C1) with an 81-fold fluorescence enhancement. Interestingly, dihydrogen phosphate causes dissociation of C1 back to free L having weak fluorescence. The methods are fast, highly selective, and allow their bare eye visualization at physiological pH. All of the interactions have been substantiated by time-dependent density functional theory calculations to rationalize their spectroscopic properties. The corresponding lowest detection limits are 1.5 × 10 -8 M for Mo(VI), 1.2 × 10 -10 M for AsO 2 - , and 3.2 × 10 -6 M for H 2 PO 4 - , whereas the respective association constants are 4.21 × 10 5 M -1 for Mo(VI), 6.49 × 10 4 M -1 for AsO 2 - , and 2.11 × 10 5 M -1 for H 2 PO 4 - . The L is useful for efficient enrichment of Mo(VI) from aqueous solution, while M1 efficiently removes AsO 2 - from environmental samples by solid-phase extraction., Competing Interests: The authors declare no competing financial interest.

A rhodamine-based smart probe ( RHES ) has been developed for trace-level detection and discrimination of multiple cations, viz. Al 3+ , Zn 2+ , Cd 2+ , and Hg 2+ in a ratiometric manner involving photo-induced electron transfer-chelation-enhanced fluorescence-fluorescence resonance energy transfer processes. The method being very fast and highly selective allows their bare eye visualization at a physiological pH. The optimized geometry and spectral properties of RHES and its cation adducts have been analyzed by time-dependent density functional theory calculations. RHES detects as low as 1.5 × 10 -9 M Al 3+ , 1.2 × 10 -9 M Zn 2+ , 6.7 × 10 -9 M Cd 2+ , and 1.7 × 10 -10 M Hg 2+ , whereas the respective association constants are 1.33 × 10 5 M -1 , 2.11 × 10 4 M -1 , 1.35 × 10 5 M -1 , and 4.09 × 10 5 M -1 . The other common ions do not interfere. The probe is useful for intracellular imaging of Zn 2+ , Cd 2+ , and Hg 2+ in squamous epithelial cells. RHES is useful for the determination of the ions in sea fish and real samples., Competing Interests: The authors declare no competing financial interest.