A triazole tethered triferrocene receptor, C40H 40O2N6Fe3 3, has been synthesized from the reaction of mono-alkynyl substituted ferrocene, 1 and 1,1′-bis-(azidomethyl)ferrocene, 2. Consequently the cation and anion sensing properties of 3 have been examined. The receptor 3 was found to be highly selective electrochemical (ΔE11/2=145mV, ΔE21/2=92mV), optical and chromogenic chemosensor for Hg2+ ion in aqueous environment. The substantial changes in its absorption spectra are accompanied by the appearance of a new low-energy peak at 631 nm (ε = 3400 M-1 cm-1). This is also accompanied by a strong color change from yellow to purple, that allows a prospective for the "naked eye" detection of Hg2+ ion over other competitor cations such as Pb2+, Cd2+, Zn2+, etc. In addition, among various anions, 3 shows a distinct electrochemical recognition of dihydrogen phosphate anion by its multiple H-bonding (C-H⋯O), which is supported by electrochemical (large cathodic shift ΔE1/2 = -175 mV) and 1H NMR titration results. © 2012 Elsevier B.V. All rights reserved.

Sundargopal Ghosh

Department Of Chemistry

ANION-SENSING PROPERTIES

Aqueous environment

CATHODIC SHIFTS

Chemosensor

Color changes

DIHYDROGEN PHOSPHATE

ELECTROCHEMICAL RECOGNITION

Ferrocenes

H-bonding

LOW-ENERGY PEAKS

MULTI-RESPONSIVE

NAKED-EYE

NMR titration

TRIFERROCENE

Iron compounds

Lead

Negative ions

Nitrogen compounds

Organometallics

physiology

Positive ions

Cadmium compounds

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Organometallic Chemistry

A unique C2 symmetric azine bridged bi-ferrocenyl receptor (4) has been modelled and synthesized. In this work, we are able to synthetically regulate conjugation of the dibenzylidenehydrazine fluorophore unit to unexpectedly reveal metal-coordination driven intramolecular twisting. The present probe shows a dramatic turn-on fluorescence response with 91 fold increment of quantum yield along with 17 nm blue shift upon binding with Hg2+ ions selectively with a limit of detection as low as 15 nM. Upon Hg2+ recognition, the ferrocene/ferrocinium redox peak was anodically shifted by ΔE1/2 = 78 mV, indicating the formation of a new complex species. A plausible binding mode of Hg2+ ions with compound 4 has been proposed based on 1H NMR titration, a high-resolution mass spectrometry (HRMS) study and a density functional theory (DFT) study along with the Job's plot analysis. Interestingly, DFT calculations have revealed that the reason for fluorescence enhancement after coordination to Hg2+ ions is not due to conventional restricted CN isomerization or interrupted N-N single bond rotation rather it is due to the increase of the π ← π∗ transition at the expense of the n → π∗ (aromatic) transition of the free ligand. Furthermore, TD-DFT calculations of the first excited singlet state of 4 and [4·Hg2+] revealed the involvement of the aromatic π electrons with the vacant site of Hg2+ ions which may be further attributed to the fluorescence enhancement phenomenon. In addition, receptor 4 was successfully applied for the detection of Hg2+ ions in real samples. © 2019 The Royal Society of Chemistry.

Dalton Transactions

Metal-coordination driven intramolecular twisting: A turn-on fluorescent-redox probe for Hg2+ ions through the interaction of ferrocene nonbonding orbitals and dibenzylidenehydrazine

The regioselective 1,3-dipolar cycloaddition reaction of alkoxy alkynyl Fischer carbene complex 1 with azidomethyl ferrocene 2 and with azidomethyl pyrene 4 under solvent-free conditions yielded the triazolyl Fischer carbene complexes 3 (C27H21O6N3FeW) and 5 (C33H21O6N3W), respectively. The cation complexation properties of these receptors have been systematically studied using electrochemical and spectroscopic techniques. The exceptional structural feature existing in these receptors is the presence of a Fischer carbene moiety, connected to the ferrocene or pyrene moiety through a 1,2,3-triazole ring. Receptor 3 contains a redox-active ferrocene moiety and is highly selective toward Pb2+ ion, whereas receptor 5, having a fluorescent pyrene unit, selectively recognizes Zn2+ and Cu 2+ ions. The binding ability of receptor 3 can be inferred either from the redox shift (the anodic shift ΔE1/2 = 55 mV) or the highly visual output response for Pb2+ ion. Receptor 5 displays considerable chelation-enhanced fluorescence (CHEF) upon binding with Zn 2+ and Cu2+ ions in an aqueous environment. Further, the proposed binding modes of these receptors and their metal cation complexation properties have been supported by 1H NMR titration and MALDI-MS and a DFT study. © 2014 American Chemical Society.

Triazolyl alkoxy Fischer carbene complexes in conjugation with ferrocene/pyrene as sensory units: Multifunctional chemosensors for lead(II), copper(II), and zinc(II) ions

A set of triazole-based chromogenic and fluorescent chemosensors with amino acid/carbohydrate-fluorophore conjugates have been designed and synthesized. The metal cation-sensing properties of glycine-anthracene, C24H 24O4N4 (3), glycine-pyrene C26H 24O4N4 (4), glucose-anthracene, C 32H33O10N3 (5) and glucose-pyrene, C34H33O10N3 (6) bio-conjugates have been studied systematically. The significant changes in their absorption spectra are accompanied by a strong color change from light yellow to brown for 3 and 4 and colorless to greenish blue for 5 and 6. Receptors 3 and 4 have potential in the "naked eye" detection of Cu2+ and 5 and 6 for Pb 2+/Hg2+ ion. The receptors 3 and 4 show fluorescence diminution following Cu2+ coordination within the limit of detection at 0.89 parts per billion (ppb) and this is unprecedented, whereas the receptors 5 and 6 present drastic fluorescence quenching upon addition of Hg2+ and Pb2+ within the limit of detection at 4 and 2 ppb respectively. Interestingly, their fluorescence and colorimetric responses are preserved in the presence of water that can be used for the selective colorimetric detection of these ions in aqueous environments. Along with the spectroscopic data, combined 1H NMR titration of the complexes and the DFT studies suggest the proposed coordination modes. © 2014 The Royal Society of Chemistry.

Fulltext

RSC Advances

Synthesis of triazole linked fluorescent amino acid and carbohydrate bio-conjugates: A highly sensitive and skeleton selective multi-responsive chemosensor for Cu(ii) and Pb(ii)/Hg(ii) ions

Mono and doubly alkynyl substituted ferrocene complexes, [Fc(CH2OCH2C{triple bond, long}CH)n], 2-3 (2: n = 1; 3: n = 2; Fc = ferrocene) have been synthesized from the room temperature reaction of mono and 1,1′-dihydroxymethyl ferrocene, Fc(CH2OH)n, 1a-b (1a: n = 1; 1b: n = 2) and propargyl bromide, in modest to good yields. These new ferrocene derivatives have been characterized by mass, IR, 1H, 13C NMR spectroscopy, and molecular structures of compound 2 and 3 were unequivocally established by single crystal X-ray diffraction study. The crystal structure analysis revealed that 2 and 3 consist of infinite 1D zig-zag hydrogen bonded chains and 2D microporous hydrogen bonded network of molecules, linked by intermolecular C-H···O hydrogen bonding. The molecular structures of both 2 and 3 are further stabilized by C-H···π interactions. © 2009 Elsevier B.V. All rights reserved.

Synthesis of mono and doubly alkynyl substituted ferrocene and its crystal engineering using -C-H···O supramolecular synthon

Organic Letters

A Bisferrocene-Benzobisimidazole Triad as a Multichannel Ditopic Receptor for Selective Sensing of Hydrogen Sulfate and Mercury Ions

A Highly Selective Colorimetric and Ratiometric Two-Photon Fluorescent Probe for Fluoride Ion Detection

Chemical Society Reviews

Recognition of amino acids by functionalized calixarenes

Analytical Chemistry

Stripping Voltammetric Detection of Mercury(II) Based on a Bimetallic Au−Pt Inorganic−Organic Hybrid Nanocomposite Modified Glassy Carbon Electrode

A triazole based triferrocene derivative as a multiresponsive chemosensor for Hg(II) ion and a redox chemosensor for H2PO4 - ion

Journal	Journal of Organometallic Chemistry
ISSN	0022328X
Open Access	No