Triazole-Linked-Thiophene Conjugate of Calix[4]arene: Its Selective Recognition of Zn2+ and as Biomimetic Model in Supporting the Events of the Metal Detoxification and Oxidative Stress Involving Metallothionein

Dinuclear Tb and Dy complexes supported by hybrid Schiff-base/calixarene ligands: synthesis, structures and magnetic properties

The synthesis of the new lanthanide complexes [HNEt3][Dy2(HL1)(L1)] (5), and [Ln2(L2)2] (Ln = TbIII (7), DyIII (8)) supported by the hybrid Schiff-base/calix[4]arene ligands H4L1 (25-[2-((2-methylphenol)imino)ethoxy]-26,27,28-trihydroxy-calix[4]arene) and H3L2 (25-[2-((2-methylpyridine)imino)ethoxy]-26,27,28-trihydroxy-calix[4]arene) are reported. Spectroscopic data (for 5) and X-ray crystallographic analysis (for 7·4MeCN, 8·4MeCN) reveal the presence of dimeric structures, featuring doubly-bridged NO4Ln(μ-O)2LnO4N (5) or N2O3Ln(μ-O)2LnO3N2 cores (7, 8) with seven-coordinated Ln3+ ions. The magnetic properties of polycrystalline samples of 5, 7 and 8 were studied by variable temperature dc and ac magnetic susceptibility measurements. The χ''(T) vs. T plots show no maxima in zero field, but the maxima can be detected under a 3 kOe dc field. The relaxation times τ obey the Arrhenius law above 5 K. Anisotropy barriers of ∼18 cm-1 (26 K) for 5 and ∼23 cm-1 (33 K) for 8 were determined.

Dinuclear lanthanide complexes supported by a hybrid salicylaldiminato/calix[4]arene-ligand: synthesis, structure, and magnetic and luminescence properties of (HNEt3)[Ln2(HL)(L)] (Ln = SmIII, EuIII, GdIII, TbIII)

Salicylaldimine/calix[4]arenes support dinuclear, triply bridged, luminescent, lanthanide complexes.

Photoluminescence properties of tetrahedral zinc(ii) complexes supported by calix[4]arene-based salicylaldiminato ligands

The synthesis and photophysical properties of four new hybrid salicylaldiminato-calix[4]arene ligands and their corresponding zinc(ii) complexes are described. The Schiff bases were obtained from condensation reactions between cone-25,27-di(aminoethoxy)-26,28-dihydroxy-calix[4]arene and salicylaldehyde (H2L1) or o-vanillin (H2L2) and 1,3-alt-25,27-di(aminoethoxy)-26,28-di(n-propyloxy)-calix[4]arene and 3,5-di-tert-butyl-salicylaldehyde (H2L3) or o-vanillin (H2L4). Complexation reactions were investigated by ESI-MS, IR, NMR, UV-vis absorption and steady-state and time resolved fluorescence spectroscopy, and X-ray crystallography. All ligands support 1 : 1 complexes (ZnL1-ZnL4), with equilibrium constants derived from absorption spectrophotometry in the range log K11 = 5.5-8.2 (MeCN or MeOH/CH2Cl2, I = 0.01 M). The zinc complexes show blue fluorescence, both in solution as well as in the solid state, with λem, Φf, and τ ranging from 472-504 nm, 0.11-0.60, and 2-9 ns, respectively. The nature of the substituents on the salicylaldiminato fragments was found to be the main parameter that influences the photophysical properties of the zinc complexes. Insights into the electronic nature of the UV-vis transitions were obtained with time dependent density functional theory (TD-DFT) calculations.

HBT-based turn-on fluorescent probe for discrimination of homocysteine from glutathione/cysteine and its bioimaging applications

In this work, we firstly reported a new type of turn-on fluorescent probe HBTI for Hcy over GSH/Cys based on ESIPT and heavy atom effect strategy.

Antidiabetic and Antilipidemic Effect of Musa balbisiana Root Extract: A Potent Agent for Glucose Homeostasis in Streptozotocin-Induced Diabetic Rat

Folklore studies have revealed that Musa balbisiana Colla (MB; Family: Musaceae) has high medicinal properties. The purpose of the present study is to evaluate antihyperglycemic, and antioxidant activity of MB extracts in streptozotocin (STZ) induced diabetic rats. In vitro antioxidant and antidiabetic activity of MB extracts, i.e., root extract (RE), shoot extract and inflorescence extract were determined by using various methods viz 1,-1-diphenyl-2-picrylhydrazyl (DPPH) and a method to assess their possible effect on glucose diffusion across gastrointestinal tract and identify bioactive compound of potent extract. In vivo antilipidemic and antidiabetic activity was evaluated by administrating oral dose of RE for 15 days on STZ- induced diabetic rat. RE showed highest antioxidant activity by scavenging DPPH radical (IC50 32.96 μg/ml) and inhibit 30% glucose movement in vitro. The methanol extract of root showed the presence of calyx [4] arene category of the compound. Furthermore, RE treated rat revealed a reduction in fasting blood glucose (62.5%), serum total cholesterol (36.2%), triglyceride (54.5%), and low-density lipoprotein (50.94%) after 15 days as compared to STZ treated animal. There was an initiation of regenerative structures of the affected organs after 15 days of RE treatment. Histopathological observations clearly differentiate the structural changes in pancreas, liver, and kidney of STZ and RE treated group. The presence of calyx [4] arene class of compound may be responsible for its antioxidant and antidiabetic properties by absorbing glucose in vivo.

Naphthyl “capped” triazole-linked calix[4]arene hosts as fluorescent chemosensors towards Fe3+ and Hg2+: an experimental and DFT computational study

The metal binding properties of four new “capped” 1,2,3-triazole linked receptors 6a–d are reported.

Sulphur-rich functionalized calix[4]arenes for selective complexation of Hg2+ over Cu2+, Zn2+ and Cd2+

ON–OFF fluorescent chemosensors based on sulphur-rich functionalized calix[4]arenes selectively bind Hg²⁺ over Cu²⁺, Zn²⁺ and Cd²⁺.

A new pyridoxal based fluorescence chemo-sensor for detection of Zn(ii) and its application in bio imaging

A new pyridoxal-based chemosensor (PydDmen) was reported for selective detection of Zn²⁺ in solution. The experimental and theoretical supports are provided to establish Zn²⁺ induced transformation of PydDmen to 3-pyridone tautomeric form.

Calixarene-based chemosensors by means of click chemistry

Click chemistry, a new strategy for organic chemistry, has been widely used in the chemical modification of calixarenes because of its reliability, specificity, biocompatibility, and efficiency. Click-derived triazoles also play a critical role in sensing ions and molecules. This in-depth review provides an overview of calixarene-based chemosensors that incorporate click-derived triazoles, and their three characteristics (chromogenic, fluorescence, and wettability) are reviewed.

Molecular Recognition and Transport of Active Pharmaceutical Ingredients on Anionic Calix[4]arene-Capped Silver Nanoparticles

A series of six anionic calix[4]arenes, having sulphonate, carboxylate, or phosphonate functions at either the para-aromatic position or the phenolic face were used to cap silver nanoparticles. Their molecular recognition properties were studied with regard to three active pharmaceutical ingredients, chlorhexidine, chloramphenicol, and. gentamycin sulfate. Of these APIs chlorhexidine is known to form cocrystals with the anionic calix[4]arenes, gentamicin sulfate is an aminoglycosidic antibiotic, and chloramphenicol is a neutral antibiotic. As expected the former two APIs show clear complexation behavior as demonstrated by shifts in the visible spectra whereas the last shows no modification in the wavelength of the plasmon resonance of the silver nanoparticles.

Highly selective and stable florescent sensor for Cd(II) based on poly (azomethine-urethane)

In this study a kind of poly(azomethine-urethane); (E)-4-((2 hydroxyphenylimino) methyl)-2-methoxyphenyl 6-acetamidohexylcarbamate (HDI-co-3-DHB-2-AP) was prepared as in the literature and employed as a new fluorescent probe for detection of Cd(II) concentration. The photoluminescence (PL) measurements were carried out in the presence of several kinds of heavy metals. HDI-co-3-DHB-2-AP gave a linearly and highly stable response against Cd(II) as decreasing a new emission peak at 562 nm. Possible interferences of other ions were found too low. Detection limit of the sensor was found as 8.86 × 10(-4) mol L(-1). Resultantly, HDI-co-3- DHB-2-AP could be effectively used as an optical Cd(II) sensor.

A Zn2+ specific triazole based calix[4]arene conjugate (L) as a fluorescence sensor for histidine and cysteine in HEPES buffer milieu

A highly fluorescent Zn(2+) complex of the triazole linked salicyl-imino-thiophenyl conjugate of calix[4]arene, [ZnL] has been demonstrated to be a chemo-sensing ensemble for the recognition of His and Cys among the naturally occurring amino acids in HEPES buffer milieu. The recognition behaviour of the [ZnL] towards these amino acids has been shown on the basis of fluorescence, absorption and visual fluorescent colour changes. The species of recognition were shown by ESI MS titrations, AFM & TEM microscopy and cell studies.

Cd2+ complex of a triazole-based calix[4]arene conjugate as a selective fluorescent chemosensor for Cys

An N,N-Dimethylamine ethylimino-appended triazole-linked calix[4]arene conjugate, L, has been synthesized and characterized, and its Cd(2+) complex has been isolated and characterized. The structure of [CdL] was established by computational calculation using B3LYP/LANL2DZ. Time-dependent density functional theory calculations were performed to demonstrate the electronic properties of [CdL]. This highly fluorescing [CdL] has been used to recognize Cys selectively among the 20 naturally occurring amino acids. [CdL] exhibits a minimum detection limit of 58 ppb for Cys, with reusability and reversibility being imparted to the system during sensing. Thus, the sensing of Cys was well demonstrated using various techniques, viz., fluorescence, absorption, visual color change, electrospray ionization MS, (1)H NMR, and live cell imaging experiments.