Crystallographic Aspects, Photophysical Properties, and Theoretical Survey of Tetrachlorometallates of Group 12 Metals [Zn(II), Cd(II), and Hg(II)] with a Triply Protonated 2,4,6-Tris(2-pyridyl)-1,3,5-triazine Ligand.

Zn(II) (complex 1), Cd(II) (complex 2), and Hg(II) (complex 3) complexes have been synthesized using a triply protonated tptz (H3tptz3+) ligand and characterized mainly by single-crystal X-ray analysis. The general formula of all of the complexes is (H3tptz)3+·Cl-·[MCl4]2-·nH2O (where n = 1, 1.5, and 1.5 for complexes 1, 2, and 3, respectively). The crystallographic analysis reveals that the anion···π, anion···π+, and several hydrogen bonding interactions play a fundamental role in the stabilization of the self-assembled architectures that in turn help to enhance the dimensionality of all of the complexes. In addition, Hirshfeld surfaces and fingerprint plots have been deployed here to visualize the similarities and differences in hydrogen bonding interactions in 1-3, which are very important in forming supramolecular architectures. A density functional theory (DFT) study has been used to analyze and rationalize the supramolecular interactions by using molecular electrostatic potential (MEP) surfaces and combined QTAIM/NCI plots. Then, the device parameters for the complexes (1-3) have been thoroughly investigated by fabricating a Schottky barrier diode (SBD) on an indium tin oxide (ITO) substrate. It has been observed that the device made from complex 2 is superior to those from complexes 1 and 3, which has been explained in terms of band gaps, differences in the electronegativities of the central metal atoms, and the better supramolecular interactions involved. Finally, theoretical calculations have also been performed to analyze the experimental differences in band gaps as well as electrical conductivities observed for all of the complexes. Henceforth, the present work combined supramolecular, photophysical, and theoretical studies regarding group 12 metals in a single frame.

Terpyridine derivatives as "turn-on" fluorescence chemosensors for the selective and sensitive detection of Zn2+ ions in solution and in live cells.

A terpyridine based compound L1 was designed and synthesized as an "off-on" chemosensor for the detection of Zn2+. Chemosensor L1 showed excellent selectivity and sensitivity toward Zn2+ by exhibiting a large fluorescence enhancement (∼51-fold) at 370 nm whereas other competitive metal ions did not show any noticeable change in the emission spectra of chemosensor L1. The chemosensor (L1) was shown to detect Zn2+ ions down to 9.76 µM at pH 7.4. However, chemosensor L1 binds Zn2+ in a 1 : 2 ratio (receptor : metal) with an association constant of 1.85 × 104 (R2 = 0.993) and this 1 : 2 stoichiometric fashion is established on the basis of a Job plot and mass spectroscopy. DFT/TD-DFT calculations were carried out to understand the binding nature, coordination features and electronic properties of L1 and the L1-2Zn2+ complex. In addition, this "turn-on" fluorescence probe was effectively used to image intracellular Zn2+ ions in cultured MDA-MB-468 cells.

Potential amelioration of nicotine-induced toxicity by nanocurcumin.

Clinical Research Curcumin, a nontoxic bioactive agent of turmeric significantly reduces nicotine-induced toxicity both at cellular and genetic levels. The clinical implication of native curcumin is hindered in the target cells due to its low aqueous solubility, poor bioavailability and poor pharmacokinetics. The problem was tried to overcome by preparing nanocurcumin with a view to improve its aqueous solubility and better therapeutic efficacy against nicotine-induced toxicity. The prepared nanocurcumin was characterized by Ultraviolet-visible spectroscopy; Field emission scanning electron microscopy (FE-SEM); X-ray diffraction (XRD); and Fourier transform infrared spectroscopy (FTIR). Female albino rats of Wistar strain were daily exposed to effective dose of nicotine (2.5 mg/kg, injected subcutaneously) and supplemented with effective dose of curcumin (80 mg/kg body weight orally) or nanocurcumin (4 mg/kg body weight orally) for 21 days. The preventive efficacies of curcumin and nanocurcumin were evaluated against the changes in liver function enzymes, kidney function parameters, lipid profiles, lipid-peroxidation, anti-oxidant status, and tissues damages etc. Results revealed that nanocurcumin more effectively ameliorated the nicotine-induced toxicities at much lower concentration due to its higher aqueous solubility and more bioavailability. The nanocurcumin can be used as a potential therapeutic agent for better efficacy against nicotine-induced toxicities than native curcumin.

Facile construction of an anthracene-decorated highly luminescent coordination polymer for the selective detection of explosive nitroaromatics and the mutagenic pollutant TNP.

Explosive nitroaromatic compounds (epNACs) are a group of chemicals that have caused significant human casualties through terrorist attacks and they also pose health risks. For the benefit of homeland security and environmental health, there is room for advancing research on the precise detection of epNACs. Coordination polymers (CPs) successfully serve this purpose because of their binding abilities and quenching capabilities. In this regard, a one-dimensional (1D) CP [Zn(bdc)(avp)2(H2O)]n (1; H2bdc = 1,4-benzenedicarboxylic acid and avp = 4-[2-(9-anthryl)vinyl]pyridine) was synthesized, which remarkably demonstrated extremely efficient ratiometric and selective sensing capacity toward epNACs and the mutagenic pollutant 2,4,6-trinitrophenol (TNP) with a quick response. Density functional theory (DFT) calculations provided a thorough analysis of the mechanistic routes behind the quenching reaction. Herein, geometrically accessible interaction sites were strategically decorated using anthracene moieties, allowing the quick and precise detection of explosive nitro derivatives and the carcinogenic pollutant TNP with increased sensitivity.

On the importance of unprecedented lone pair-salt bridge interactions in Cu(II)-malonate-2-amino-5-chloropyridine-perchlorate ternary system.

A Cu(II)-malonate complex with formula {(C5H6N2Cl)12[Cu(1)(C3H2O4)2][Cu(2)(C3H2O4)2(H2O)2][Cu(4)(C3H2O4)2][Cu(3)(C3H2O4)2(H2O)2](ClO4)4}n (1) [C5H6N2Cl = protonated 2-amino-5-chloropyridine, C3H4O4 = malonic acid, ClO4(-) = perchlorate] has been synthesized from purely aqueous media simple by mixing the reactants in their stoichiometric ratio, and its crystal structure has been determined by single-crystal X-ray diffraction. In 1, copper(II) malonate units form infinite 1D polymeric chains, which are interlinked by hydrogen bonds to generate 2D sheets. These 2D sheets are joined side by side primarily by various hydrogen bonds to form a 3D structure. A multitude of salt bridges are formed in this structure, connecting the protonated 2-amino-5-chloropyridines and the malonate ligands of the polymeric polyanion. Examining this characteristic of the solid-state architecture, we noticed several salt-bridge (sb)···π interactions and an unexplored interaction between the lone pair (lp) of one malonate oxygen atom and a planar salt bridge. The combination of this interaction with various other weak intermolecular forces results in a remarkably extended supramolecular network combining a wide variety of interactions involving π-systems (Cl···π, π···π) and salt bridges (sb···π and lp···sb). We describe the energetic and geometric features of this lone pair-salt-bridge interaction and explore its impact on the resultant supramolecular organization using theoretical DFT-D3 calculations.

Anion induced formation of supramolecular associations involving lone pair-π and anion-π interactions in Co(II) malonate complexes: experimental observations, Hirshfeld surface analyses and DFT studies.

Three Co(II)-malonate complexes, namely, (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](NO(3))(2) (1), (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](ClO(4))(2) (2), and (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](PF(6))(2) (3) [C(5)H(7)N(2) = protonated 2-aminopyridine, C(3)H(4)O(4) = malonic acid, NO(3)(-) = nitrate, ClO(4)(-) = perchlorate, PF(6)(-) = hexafluorophosphate], have been synthesized from purely aqueous media, and their crystal structures have been determined by single crystal X-ray diffraction. A thorough analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions in 1-3, which are crucial in building supramolecular architectures. When these complexes are structurally compared with their previously reported analogous Ni(II) or Mg(II) compounds, a very interesting feature regarding the role of counteranions has emerged. This phenomenon can be best described as anion-induced formation of extended supramolecular networks of the type lone pair-π/π-π/π-anion-π/π-lone pair and lone pair-π/π-π/π-anion involving various weak forces like lone pair-π, π-π, and anion-π interactions. The strength of these π contacts has been estimated using DFT calculations (M06/6-31+G*), and the formation energy of the supramolecular networks has been also evaluated. The influence of the anion (NO(3)(-), ClO(4)(-), and PF(6)(-)) on the total interaction energy of the assembly is also studied.

Objective and Subjective Analysis for Efficaciousness of Nasal Airway in Patients Undergoing Conventional and Endoscopic Septoplasty: A Comparative Study.

Deviated nasal septum is the most common cause of nasal obstruction and is one of the common problems encountered by otolaryngologists. Although there are different methods to surgically correct a deviated nasal septum which can give qualitative relief to the patient, less emphasis is put on the quantitative assessment of airway after a septal correction surgery. Institution based Case Control study was undertaken at Medical College and Hospital Kolkata between January 2019 to March 2020 to subjectively and objectively assess and compare the nasal airway status preoperatively and postoperatively in patients undergoing conventional and endoscopic septoplasty. A total of 250 patients were taken in this study and divided into two groups A and B. Group A consisted of patients undergoing Conventional Septoplasty (Control arm) and Group B consisted of patients undergoing Endoscopic Septoplasty (Case arm). Patients were followed up and the readings of NOSE score and PNIF value were recorded at the end of 6 weeks and 6 months (24 weeks). The Mean NOSE score post operatively at the end of 6 weeks was 36.32 in GROUP A (Control arm) and 33.08 in GROUP B (Case arm). t-Test revealed insignificant results with a p-value of 0.08. The mean NOSE score post operatively at the end of 6 months was 29.96 in GROUP A (Control arm) and 22.16 in GROUP B (Case arm). t-Test revealed significant results with a p-value of 0.00. Similarly, Mean PNIF value post operatively at the end of 6 weeks was 57.24 in GROUP A (Control arm) and 73.88 in GROUP B (Case arm). t-Test revealed significant results with p-value of 0.00. The mean PNIF value post-operatively at the end of 6 months was 59.44 in GROUP A (Control arm) and 80.08 in GROUP B (Case arm). t-Test revealed significant results with p-value of 0.00. Endoscopic Septoplasty is a very effective way to treat septal deviations especially with deviations based on the posterior aspect of the septum. It provides a superior edge in terms of nasal airway improvement as compared to conventional method of septoplasty. Supplementary Information: The online version contains supplementary material available at 10.1007/s12070-022-03120-2.

Mechanistic studies on the oxidation of ascorbic acid and hydroquinone by a {Mn4O6}4+ core in aqueous media.

Described in this work is the kinetics of oxidation of ascorbic acid and hydroquinone by a tetranuclear Mn(IV) oxidant, [Mn(4)(µ-O)(6)(bipy)(6)](4+) (1(4+), bipy =2,2(/)-bipyridine), in aqueous solution over a wide pH range 1.5-6.0. In particular, below pH 3.0, protonation on the oxo-bridge of 1(4+) results in the formation of [Mn(4)(µ-O)(5)(µ-OH)(bipy)(6)](5+) (1H(5+)) as an additional oxidant over 1(4+). Both ascorbic acid and ascorbate whereas only hydroquinone and none of its protolytic species were found to be reactive reducing agents in these reactions. Analysis of the rate data clearly established that the oxo-bridge protonated oxidant 1H(5+) is kinetically far more superior to 1(4+) in oxidizing ascorbic acid and hydroquinone. Rates of these reactions are substantially lowered in D(2)O-enriched media in comparison to that in H(2)O media. An initial one electron one proton transfer electroprotic rate step could be mechanistically conceived. DFT studies established that among the two sets of terminal and central Mn(IV) atoms in the tetranuclear oxidant, one of the two terminal Mn(IV) is reduced to Mn(III) at the rate step that we can intuitively predict considering the probable positive charge distribution on the Mn(IV) atoms.

Design and synthesis of a sulphur containing Schiff base drug: DNA binding studies and theoretical calculations.

The Schiff base compound MTA ((E)-5-methyl-N'-((5-methylthiophen-2-yl)methylene)-1H-pyrazole-3-carbohydrazide) derived from 2-thiophenecarboxaldehyde and 5-methylpyrazole-3-carbohydrazide has been designed to develop new sulphur containing DNA targeted molecule. The MTA has been characterized by elemental analyses, 1H-NMR, single crystal X-ray diffraction studies as well as by geometry optimization of using DFT/B3LYP. The interaction of MTA with Calf thymus DNA (CT-DNA) was studied by spectroscopic and calorimetric techniques. The synthesized compound was found to bind with CT-DNA through groove binding mode, and the binding constant was estimated to be (4.15 ± 0.08) × 104 M-1. The negative ΔG0 and positive ΔS0 values obtained from the calorimetric technique confirmed the spontaneity of the binding of MTA with DNA.Communicated by Ramaswamy H. Sarma.

Influence of 2-Amino-4-methylpyridine and 2-Aminopyrimidine Ligands on the Malonic Acid-Cu(II) System: Insights through Supramolecular Interactions and Photoresponse Properties.

Two Cu(II)-malonate complexes with 2-amino-4-methylpyridine (complex 1) and 2-aminopyrimidine (complex 2) auxiliary ligands were synthesized, and their single-crystal X-ray diffraction structures were established. Change in the auxiliary ligand exhibits substantial structural variation in the present complexes. Complex 1 shows a one-dimensional anionic copper-malonate moiety connected by the malonate bridge, whereas complex 2 is a mononuclear one. For both the complexes, auxiliary ligands are attached with the Cu-malonate moiety through various noncovalent interactions. Optical band gap, electrical conductivity, and photosensitivity of complexes 1 and 2 were measured, but the values of electrical parameters of the complexes significantly differ from each other. However, the magnitudes of electrical parameters increase several times for both the complexes when they are exposed under visible light, though the values of light sensing parameters of complex 1 were found to be higher than those of complex 2. Density functional theory calculations for complex 1 were carried out to support the experimental result.

Supramolecular lone pair-pi/pi-pi/pi-anion assembly in a Mg(II)-malonate-2-aminopyridine-nitrate ternary system.

The solid-state structure of an alkaline-earth metal complex reveals the formation of a remarkable supramolecular framework based on concurrent lone pair-pi, pi-pi, and pi-anion interactions whose stability has been investigated by density functional theory.

Water-chloride and water-bromide hydrogen-bonded networks: influence of the nature of the halide ions on the stability of the supramolecular assemblies.

Two compounds, namely, [TTPH(2)](Cl)(2) x 4 H(2)O (1) and [TTPH(2)](Br)(2) x 4 H(2)O (2), (TTP = 4'-p-tolyl-2,2':6',2''-terpyridine) were synthesized from purely aqueous media and characterized by physical techniques. In the solid-state structures of these compounds, interesting supramolecular assemblies are observed. In 1, an unusual staircase-like architecture of the tape of edge-shared planar water hexamer is of importance, where the chloride ions are at the two edges of the tape. In 2, the polymeric nature of the water-bromide assembly is of interest, where discrete open-cube water octamers are doubly bridged by bromide ions. Semiempirical and DFT calculations confirm that the nature of the anion indeed affects the topology of the water-halide assemblies. We conclude that the protonated [TTPH(2)](2+) species can act as appropriate receptors for halide ions, which in turn act as a matrix for the formation of polymeric 1D water-halide assemblies.

Elucidating the chemical and biochemical applications of Citrus sinensis-mediated silver nanocrystal.

Synthesis of nanoparticles using biodegradable source is safer and echo-friendly. Here, we describe the synthesis of polycrystalline silver nanocrystals using Citrus sinensis acting as both reducing and capping agents. After exposing the silver ions to orange extract, rapid reduction of silver ions led to the formation of stable silver nanocrystals due to the reducing and stabilizing properties of orange fruit juice. The synthesized silver nanocrystals were characterized using various analytical techniques like UV-vis spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The biochemical activity of the synthesized nanocrystals was studied in the light of affinity to bovine serum albumin using several biophysical methods like absorbance, fluorescence and circular dichroism spectroscopy. Cytotoxic activity of these nanocrystals was also studied against Hep-2 cell line using fluorescence microscopy. It was also found that the synthesized nanocrystals can sense mercuric ion down to 50 µM in the presence of a number of cations. Furthermore, we established that the silver nanoparticles can effectively catalyse the reduction of methylene blue by ascorbic acid. The present study will enrich our knowledge on the chemical and biochemical activities of green-synthesized silver nanocrystals.

Structures, Photoresponse Properties, and Biological Activity of Dicyano-Substituted 4-Aryl-2-pyridone Derivatives.

Described in this work is the synthesis of a novel dicyano-substituted N-2-aminoethyl-4-(3-pyridinyl)-2-pyridone organic compound (1) that is characterized by several spectroscopic methods. Compound (1) was utilized for the preparation of its perchlorate (2), chloride (3), and bromide (4) salts. Single-crystal X-ray structures of these three salts were determined, and noncovalent weak interactions involving the aromatic rings, anions, and water molecules in (2-4) were investigated in detail. Solid-state UV-vis spectrum of the reported compounds (1-4) was utilized to calculate their optical band gaps, which clearly indicated that they belong to the semiconductor family. Under illumination condition, the magnitudes of electrical properties of (1) and its salts (2-4) improve remarkably although the improvement differs from salt to salt and the result was analyzed theoretically. Salt (2) was tested for its DNA binding ability.

Structures, photoresponse properties and DNA binding abilities of 4-(4-pyridinyl)-2-pyridone salts.

Three salts [perchlorate (2), chloride (3) and tetrafluoroborate (4)] were synthesized from a 1-(2-aminoethyl)-6-hydroxy-2-oxo-1,2-dihydro-[4,4'-bipyridine]-3,5-dicarbonitrile compound (1) and characterized by spectroscopic and single crystal X-ray diffraction methods. Various noncovalent interactions (e.g., anion⋯π+, π⋯π, lp⋯π) are explored in the solid state crystal structure of the salts. Optical band gaps of all the four compounds were determined from their solid-state UV-vis spectrum. Electrical properties like electrical conductivity, photosensitivity, etc. were calculated and the results revealed that they have potential to act as optoelectronic devices. The values of the electrical parameters increase several times when they are exposed to visible light rather than in dark conditions. The light sensing properties of the salts (2-4) are enhanced compared to that of the mother organic compound 1 but the magnitude of this enhancement is not same for the three salts. This observation has been rationalized by theoretical considerations. Moreover, the DNA binding ability of one of the representative salts (compound 2) was examined to check the biological importance of the synthesized salts.

Coordination Polymers Based on Phthalic Acid and Aminopyrazine Ligands: On the Importance of N⁻H···π Interactions.

Two new Co(II) and Cu(II) coordination polymers, {Co(HL1)2(µ-L2)(H2O)2}n (1) and {[Cu(HL1)2(µ-L2)H2O]·H2O}n (2) (H2L1 = Phthalic acid and L2 = 2-aminopyrazine), have been synthesized by slow evaporation of solvent and characterized by IR spectroscopic, elemental, single-crystal X-ray diffraction and thermal analysis. X-ray results indicate that in both the polymers, phthalate acts as a monodentate ligand and the aminopyrazine ligand is responsible for the formation of the infinite one-dimensional chain structure. The solid-state structures are stabilized through hydrogen bonds and N‒H···π interactions by generating two-dimensional layered structures. Finally, the non-covalent interactions have been studied energetically and using Bader's theory of atoms in molecules by means of Density Functional Theory (DFT) calculations. The influence of the metal coordination on the strength of the interaction has been studied using molecular electrostatic potential surface calculations.

Enhanced Photosensitive Schottky Diode Behavior of Pyrazine over 2-Aminopyrimidine Ligand in Copper(II)-Phthalate MOFs: Experimental and Theoretical Rationalization.

Two novel Cu(II)-based metal-organic frameworks [C40H34Cu2N6O18 (1) and C20H18CuN2O10 (2)] have been synthesized using 2-aminopyrimidine or pyrazine ligands and phthalate ion and characterized spectroscopically and by X-ray single-crystal diffraction. Both 1 and 2 show electrical conductivity and photosensitivity, evidencing their potentiality in optoelectronic device applications. Experimental and theoretical investigations revealed that the electrical conductivity under irradiation of visible light increases compared to that under dark condition (photosensitive Schottky barrier diode behavior), especially in complex 2. Both 1 and 2 have been successfully applied in technologically challenging thin-film active devices.

Advancing Cholesteatoma Secondary to Acquired Atresia of the External Auditory Canal: Clinical Perspectives.

Acquired atresia of External Auditory Canal (EAC) is seldom encountered in routine otolaryngology practice. Apart from resulting in moderate-to-severe conductive hearing impairment, it is a potentially dreaded condition which might lead to canal cholesteatoma. Suspected to develop as a consequence of a pre-existing chronic otitis externa/media, the EAC atresia leads to proximal (medial) accumulation of desquamated epithelium and denatured keratin (the canal cholesteatoma) that further leads to aggravation of the chronic otitis, thereby initiating a vicious cycle. The canal cholesteatoma might progress unhindered into the middle ear and mastoid cavity, with its characteristic bone-eroding property, producing complications. A high index of clinical suspicion along with proper imaging are therefore essential to apprehend the disease progression in a patient presenting with an apparently innocuous EAC stenosis/atresia. In this report, we illustrate the clinical details of a young girl with unilateral acquired EAC atresia where canal cholesteatoma had turned extensive, invaded the middle ear cleft, and produced a post-aural fistula, thereby establishing one of the extreme outcomes of chronic otitis.

On the Importance of Noncovalent Carbon-Bonding Interactions in the Stabilization of a 1D Co(II) Polymeric Chain as a Precursor of a Novel 2D Coordination Polymer.

A new cobalt(II) coordination polymer 2 with µ1,5 dicyanamide (dca) and a bidentate ligand 3,5-dimethyl-1-(2'-pyridyl)pyrazole (pypz) is prepared in a stepwise manner using the newly synthesized one-dimensional linear Co(II) coordination polymer 1 as a precursor. The structural and thermal characterizations elucidate that the more stable complex 2 shows a two-dimensional layer structural feature. Here, Co(II) atoms with µ1,5 dicyanamido bridges are linked by the ligand pypz forming a macrocyclic chain that runs along the crystallographic 'c' axis having 'sql' (Shubnikov notation) net topology with a 4-connected uninodal node having point symbol {4(4).6(2)}. The remarkable noncovalent carbon-bonding contacts detected in the X-ray structure of compound 1 are analyzed and characterized by density functional theory calculations and the analysis of electron charge density (atoms in molecules).

Biochemical activity of a fluorescent dye rhodamine 6G: Molecular modeling, electrochemical, spectroscopic and thermodynamic studies.

Interaction of CT DNA with Rhodamine 6G (R6G) has been studied using molecular docking, electrochemical, spectroscopic and thermodynamic methods. From the study, it was illustrated that Rhodamine 6G binds to the minor groove of CT DNA. The binding was cooperative in nature. Circular voltametric study showed significant change in peak current and peak potential due to complexation. All the studies showed that the binding constant was in the order of 106M-1. Circular dichroic spectra showed significant conformational change on binding and DNA unwind during binding. Thermodynamic study showed that binding was favored by negative enthalpy and positive entropy change. From thermodynamic study it was also observed that several positive and negative free energies played significant role during binding and the unfavorable conformational free energy change was overcame by highly negative hydrophobic and salt dependent free energy changes. The experimental results were further validated using molecular docking study and the effect of structure on binding has been studied theoretically. From docking study it was found that the hydrophobic interaction and hydrogen bonds played a significant role during binding. The dye was absorbed by cell and this phenomenon was studied using fluorescent microscope. Cell survivability test showed that the dye active against Human Breast Cancer cells MDA-MB 468. ROS study showed that the activity is due to the production of reactive oxygen.