Eco-friendly chitosan Schiff base as an efficient sensor for trace anion detection.

Herein, a chitosan Schiff base sample (CSAN) was strategically designed and prepared via a two-step process. In the first step, an azo derivative of 1- naphthylamine namely, [2-hydroxy-5-(naphthalene-1-yldiazenyl) benzaldehyde] (HNDB) was synthesized as an aldehyde moiety. Then the condensation reaction of HNDB with chitosan afforded CSAN as the target product. Structural analyses of synthesized material were accomplished through FT-IR, 1H NMR, UV-Vis, XRD, TGA, and SEM spectral methods. Meanwhile, the heterogeneous CSAN was able to detect the presence of hydrogen carbonate (HCO3-), acetate (AcO-), and cyanide (CN-) anions in semi-aqueous media (H2O/DMSO; 10:90%, v/v). Moreover, the selectivity of CSAN towards CN- anion was increased through variation in solvent mixture ratios. Thereupon, CSAN was explored as a promising sensor towards CN- anion in an aqueous media through considerable color variation from colorless to pale yellow as well as quantitative chemical analysis. Overall, reliable CSAN chemosensor with high sensitivity for mentioned anions has a pivotal role in practical applications owing to it's reversibility ability.

Application of a new metal-organic framework of [Ni2F2(4,4'-bipy)2(H2O)2](VO3)2.8H2O as an efficient adsorbent for removal of Congo red dye using experimental design optimization.

The new metal-organic framework of [Ni2F2(4,4'-bipy)2(H2O)2](VO3)2.8H2O was synthesized by a sonochemical method for the adsorptive removal of Congo red (CR) in a batch system. It was characterized by infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), thermogravimetric (TGA), and elemental analyses. Box-Behnken design (BBD) was applied to obtain an appropriate regression model for removal percent (R%) of CR dye. The optimized conditions for three effective factors: adsorbent dosage, temperature, and CR concentration were m = 0.0107 g, T = 45 °C, and Cd = 50 mg.L-1, respectively, while maximum removal percent is 96%. Langmuir isotherm shows that the maximum monolayer adsorption capacity (qmax) is 242.1 mg.g-1. The pseudo-second-order kinetic model better describes the adsorption kinetics behavior. Thermodynamic parameters illustrate that the adsorption process is endothermic and spontaneous chemisorption. The aim of this study is the introduction of a new metal-organic framework that can adsorb Congo red with high adsorption capacity. Therefore, due to synthesis of the new metal-organic framework as a high efficient adsorbent for Congo red removal, and also multivariate optimization of removal conditions, this study outright is novel.

Simultaneous measurement of hydrogen carbonate and acetate anions using biologically active receptor based on azo derivatives of naphthalene.

A novel receptor based on azo-derivatives of 1-naphthylamine (2-((E)-((4-chloro-3-(trifluoromethyl)phenyl)imino)methyl)-4-((E)-naphthalene-1-yldiazenyl)phenol(2) abbreviated CTNP was successfully designed and synthesized. Its sensing properties were studied deeply. Systematic studies of CTNP with HCO3- and AcO- anions in DMSO disclosed that there is hydrogen-bonding between CTNP and incoming anions. Significant changes in the visible region of the spectrum, as well as a drastic color change of CTNP from pale yellow to red, observed due to interaction as mentioned earlier. The stoichiometry of [CTNP: HCO3- or AcO-] complexes and association constants determined through Job's method and Benesi-Hildebrand (B-H) plot, respectively. Taking into account the analysis results, CTNP performs the selective recognition of sub-millimolar concentrations of HCO3- and AcO- efficiently. The antifungal activity of the receptor was tested against Aspergillus brasiliensis and Aspergillus niger. CTNP exhibited excellent antifungal activity against both strains. CTNP also represented antibacterial activity against Gram-positive bacteria: Staphylococcus epidermidis. It was cleared that designed receptor can be applied under physiological conditions for a long duration.

Synthesis and studies of selective chemosensor for naked-eye detection of anions and cations based on a new Schiff-base derivative.

A new chromogenic receptor, 4-((2,4-dichlorophenyl)diazenyl)-2-(3-hydroxypropylimino) methyl)phenol, has been designed and synthesized for quantitative and low-cost detection of various biological anions and cations. The dye was characterized by elemental analyses, infrared, UV-visible spectroscopy, and NMR spectroscopy. Upon the addition of F(-) and H2PO4(-) to the solution of chemosensor in DMSO, the dramatic naked eye detectable color changes were observed from yellow to red and orange with a limit of detection (LOD) of 1.66×10(-6)mol. L(-1) and 1.24×10(-6)mol. L(-1) at room temperature, respectively. The chemosensor showed visual changes towards cations, such as Al(3+), Cu(2+), Fe(3+), and Cr(3+), in DMSO/water (9:1). The detection limit of receptor L for the analysis of Al(3+) ion was calculated to be 3.02×10(-6)mol. L(-1). The anion recognition property of the receptor via proton transfer was monitored by UV-visible titration and (1)HNMR spectroscopy. The binding constant (Ka) and stoichiometry of the host-guest complexes formed were determined by the Benesi-Hildebrand (B-H) plot and Job's method, respectively.

Effect of cooperativity in lithium bonding on the strength of halogen bonding and tetrel bonding: (LiCN)n···ClYF3 and (LiCN)n···YF3Cl (Y = C, Si and n = 1-5) complexes as a working model.

This paper reports results of cooperativity in lithium bonding on the strength of halogen bonding and tetrel bonding in complexes pairing CF3Cl and SiF3Cl with (LiCN)n complexes, where n varies from 1 to 5. Molecular geometries and stabilization energies of title complexes are calculated at the MP2 level with 6-311++G(d,p) basis set. Cooperative effects are found in terms of structural and energetic properties when lithium, halogen, and tetrel bonds are present in these complexes simultaneously. Our results reveal that strength of halogen and tetrel bondings are enhanced due to cooperativity of Li···N interactions in lithium bonded complexes. Good linear correlations between cooperativity parameters and electronic properties of complexes were established in the present study.

Survival from skin cancer and its associated factors in Kurdistan province of Iran.

BACKGROUND: We explored survival of skin cancer and its determinants in Kurdistan province of Iran. METHODS: In a retrospective cohort design, we identified all registered skin cancer patients in Kurdistan Cancer Registry from year 2000 to 2009. Information on time and cause of death were obtained from Registrar's office and information on type, stage and anatomic locations were extracted from patients' hospital records. Additional demographic information was collected via a telephone interview. We calculated the 3 and 5 years survival. Survival experiences in different groups were compared using log rank test. Cox proportional hazard model was built and hazard ratios and their 95% confidence intervals were calculated. RESULTS: Of a total of 1353, contact information for 667 patients were available, all of which were followed up. 472 telephone interviews were conducted. Mean follow-up time was 34 months. We identified 78 deaths in this group of patients and 44 of them were because of skin cancer. After controlling for confounding, tumour type, anatomical location, and diseases stage remained significantly associated with survival. Hazard ratios for death because of squamous cell carcinoma was 74.5 (95%CI: 4.8-1146) and for melanoma was 24.4 (95%CI: 1.3-485) compared with basal cell carcinomas. Hazard ratio for tumours in stage 4 was 16.7 (95%CI: 1.8-156.6) and for stage 3 was 16.8 (95%CI: 1.07-260) compared with stage 1 and 2. CONCLUSION: Tumour stage is independently associated with survival. Relatively low survival rates suggest delayed diagnosis. Increasing public awareness through media about the warning signs of skin cancers could increase the chance of survival in these patients.

Drastic effect of lattice propionitrile molecules on the spin-transition temperature of a 2,2'-dipyridylamino/s-triazine-based iron(II) complex.

Reaction of iron(II) selenocyanate (obtained from Fe(ClO4)2 and KNCSe) with 2-(N,N-bis(2-pyridyl)amino)-4,6-bis(pentafluorophenoxy)-(1,3,5)triazine (L1(F)) in propionitrile produces the compound [Fe(L1(F))2(NCSe)2]·2CH3CH2CN (1(NCSe)·2PrCN), which shows spin-crossover (SCO) properties characterized by a T(1/2) of 283 K and a ΔT80 (i.e., temperature range within which 80% of the transition considered occurs) of about 65 K. Upon air exposure, 1(NCSe)·2PrCN gradually converts to a new SCO species that exhibits different properties, as reflected by T(1/2) = 220 K and ΔT80 = 70 K. Various characterization techniques, namely, IR spectroscopy, thermogravimetric analysis, and thermodiffractometric studies, reveal that the new phase is obtained through the loss of the lattice propionitrile molecules within several days upon air exposure or several hours upon heating above 390 K.

Enhancement of spin-crossover cooperativity mediated by lone pair-π interactions and halogen bonding.

Rational ligand design has allowed the generation of a highly cooperative spin-transition iron(II) complex, an unprecedented result in the family of (2,2'-dipyridylamino/s-triazine)-based SCO materials.

Synthesis, spectroscopy, thermal analysis, magnetic properties and biological activity studies of Cu(II) and Co(II) complexes with Schiff base dye ligands.

Three azo group-containing Schiff base ligands, namely 1-{3-[(3-hydroxypropylimino) methyl]-4-hydroxyphenylazo}-4-nitrobenzene (2a), 1-{3-[(3-hydroxypropylimino) methyl]-4-hydroxyphenylazo}-2-chloro-4-nitrobenzene (2b) and 1-{3-[(3-hydroxypropylimino) methyl]-4-hydroxyphenylazo}-4-chloro-3-nitrobenzene (2c) were prepared. The ligands were characterized by elemental analysis, FTIR spectroscopy, UV-Vis spectroscopy, ¹³C- and ¹H-NMR spectroscopy and thermogravimetric analysis. Next the corresponding copper(II) and cobalt(II) metal complexes were synthesized and characterized by the physicochemical and spectroscopic methods of elemental analysis, FTIR spectroscopy, UV-Vis spectroscopy, magnetic moment measurements, and thermogravimetric analysis (TGA) and (DSC). The room temperature effective magnetic moments of complexes are 1.45, 1.56, 1.62, 2.16, 2.26 and 2.80 B.M. for complexes 3a, 3b, 3c, 4a 4b, and 4c, respectively, indicating that the complexes are paramagnetic with considerable electronic communication between the two metal centers.

New asymmetric heptaaza Schiff base macrocyclic complex of Mn(II): Crystal structure, biological and DFT studies.

A new asymmetric heptaaza Schiff base macrocyclic bis(pendant donor) manganese(II) complex, [MnL(1)](ClO(4))(2).CH(3)CN (1), has been prepared and characterized by X-ray diffraction and spectroscopic methods. The antimicrobial activity of 1 and a series of its familiar symmetric heptaaza [15]pydieneN(5), [16]pydieneN(5), and [17]pydieneN(5)-based bis-(2-aminoethyl) pendant armed Schiff base macrocyclic complexes of Mn(II) were tested against Escherichia coli, Staphylococcus aureus and Candida albicans. The results showed that the symmetric heptaaza [16]pydieneN(5), and [17]pydieneN(5)-based Schiff base macrocyclic complexes of Mn(II) had remarkable inhibition zone on the culture of S. aureus and E. coli as compared with standard drugs. The optimized geometry of the prepared complex has been obtained from density functional method, DFT, using B3LYP/6-31G* basis set.