Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea.

Low-Temperature In Situ Amino Functionalization of TiO2 Nanoparticles Sharpens Electron Management Achieving over 21% Efficient Planar Perovskite Solar Cells.

Abstract: Titanium oxide (TiO2 ) has been commonly used as an electron transport layer (ETL) of regular-structure perovskite solar cells (PSCs), and so far the reported PSC devices with power conversion efficiencies (PCEs) over 21% are mostly based on mesoporous structures containing an indispensable mesoporous TiO2 layer. However, a high temperature annealing (over 450 °C) treatment is mandatory, which is incompatible with low-cost fabrication and flexible devices. Herein, a facile one-step, low-temperature, nonhydrolytic approach to in situ synthesizing amino-functionalized TiO2 nanoparticles (abbreviated as NH2 -TiO2 NPs) is developed by chemical bonding of amino (-NH2 ) groups, via TiN bonds, onto the surface of TiO2 NPs. NH2 -TiO2 NPs are then incorporated as an efficient ETL in n-i-p planar heterojunction (PHJ) PSCs, affording PCE over 21%. Cs0.05 FA0.83 MA0.12 PbI2.55 Br0.45 (abbreviated as CsFAMA) PHJ PSC devices based on NH2 -TiO2 ETL exhibit the best PCE of 21.33%, which is significantly higher than that of the devices based on the pristine TiO2 ETL (19.82%) and is close to the record PCE for devices with similar structures and fabrication procedures. Besides, due to the passivation of the surface trap states of perovskite film, the hysteresis of current-voltage response is significantly suppressed, and the ambient stability of devices is improved upon amino functionalization.

Preparation of new superhydrophobic and highly oleophobic polyurethane coating with enhanced mechanical durability

Abstract: In this study, a noble robust superhydrophobic and highly oleophobic polyurethane (PU)–SiO2 nanoparticle (NP) coating is specially designed using sol-gel process. For this purpose the effective parameters on surface tension and durability of the synthesized coating investigated and optimized. This new superhydrophobic and highly oleophobic coating exhibits good pensile hardness as high as 6H with adhesive force grade of 5B and repels water and oil with contact angles (CAs) of 159° and 140°, respectively. The synthesized PU-SiO2 composite also retains an excellent amphiphobicity after a 7 days immersion in water with water and oil with CAs of 150° and 130°. Facile fabrication of PU–SiO2 coating with enhanced amphiphobicity and durability provides a novel pathway to the development of a high performance superamphiphobic surfaces. The outstanding properties of synthesized PU–SiO2 coating are mainly due to (i) reduction of surface energy by fluoroalkylsilanes, (ii) formation of hierarchical micro- and nanometer scale roughness structures on the coating surface, (iii) stable adhesion of SiO2 NPs into PU resin after cross-linking with isocyanate, and (iv) improving the chemical bonding and electrostatic interactions between film and substrate.

A hybrid LIBS–Raman system combined with chemometrics: an efficient tool for plastic identification and sorting

Abstract: Classification of plastics is of great importance in the recycling industry as the littering of plastic wastes increases day by day as a result of its extensive use. In this paper, we demonstrate the efficacy of a combined laser-induced breakdown spectroscopy (LIBS)–Raman system for the rapid identification and classification of post-consumer plastics. The atomic information and molecular information of polyethylene terephthalate, polyethylene, polypropylene, and polystyrene were studied using plasma emission spectra and scattered signal obtained in the LIBS and Raman technique, respectively. The collected spectral features of the samples were analyzed using statistical tools (principal component analysis, Mahalanobis distance) to categorize the plastics. The analyses of the data clearly show that elemental information and molecular information obtained from these techniques are efficient for classification of plastics. In addition, the molecular information collected via Raman spectroscopy exhibits clearly distinct features for the transparent plastics (100% discrimination), whereas the LIBS technique shows better spectral feature differences for the colored samples. The study shows that the information obtained from these complementary techniques allows the complete classification of the plastic samples, irrespective of the color or additives. This work further throws some light on the fact that the potential limitations of any of these techniques for sample identification can be overcome by the complementarity of these two techniques.

Copper complexes for biomedical applications: Structural insights, antioxidant activity and neuron compatibility.

Abstract: Copper coordinated with amino acid residues is essential for the function of many proteins. In addition, copper complexed to free l -Histidine, as [Cu(His)2], is used in the treatment of the neurodegenerative Menkes disease and of cardioencephalomyopathy. This study was aimed to coordinate copper(II) with four small ligands ( l -Serine, l -Histidine, Urea and Biuret) and to evaluate structural features, stability, antioxidant activity and neuronal compatibility of the resulting complexes. All complexes were synthesized with CuCl2 and purified by precipitation in alcohol. Elemental composition, X-rays diffraction and FTIR indicated that the complexes were in form of [Cu(ligand)2] and exhibited tridentate ( l -Histidine), bidentate ( l -Serine and Biuret) or monodentate (Urea) coordination with copper. UV–Vis absorbance profiles in physiologically relevant solutions and cyclic voltammetry revealed that, contrarily to [Cu(Urea)2Cl2] and [Cu(Biuret)2Cl2], the [Cu(Ser)2] and [Cu(His)2Cl2] complexes were stable in different media including water, physiological saline and intestinal-like solutions. All complexes and their ligands had antioxidant capacity as evaluated by DPPH (1,1-diphenyl-2,2-picrylhydrazyl) and DPD (N,N-diethyl-p-phenylenediamine) methods, and the [Cu(His)2Cl2] complex was the most potent. Neuronal compatibility was assessed through cell viability measurements using cultured neurons derived from mouse P19 stem cells. Although only [Cu(His)2Cl2] showed a good neurocompatibility (about 90% at concentrations up to 200 μM), the cytotoxicity of the other copper complexes was lower compared to equivalent concentrations of CuCl2. These findings open new perspectives for the use of these copper complexes as antioxidants and possibly as therapeutic agents for neurodegenerative diseases. Furthermore, study of these complexes may help to improve chelation therapy for copper dysfunctions.

In vitro concentration dependent detection of creatinine: a surface enhanced Raman scattering and fluorescence study

Abstract: An attempt has been made to detect the concentration of creatinine in a very dilute aqueous solution in vitro on the basis of the Jaffe reaction, the commonly used reaction for clinical determination of creatinine concentration in blood serum or urine. For this various spectroscopic techniques viz. Raman spectroscopy, surface enhanced Raman scattering, UV-visible and fluorescence spectroscopy have been used. As a result of the Jaffe reaction using aqueous solutions of creatinine at different concentrations and picric acid and NaOH as reagents, a reddish orange colored Jaffe complex is produced. The concentration dependent SERS spectra of the Jaffe complex show gradual decrease in the intensity of ring deformation mode of creatinine on decreasing creatinine concentration. The concentration dependent absorption spectra of the Jaffe complex show changes in intensity in one of the absorption peaks characteristic of creatinine. The concentration dependent fluorescence emission spectra of the Jaffe complex show a blue shift in emission maxima on reducing the concentration of creatinine in the solution. The observed results suggest the possibility to detect the concentration of creatinine in a very dilute solution in vitro by SERS and fluorescence techniques and the application of these techniques in vivo might aid in a more specific and accurate determination of creatinine in serum or urine.

Density‐functional thermochemistry. III. The role of exact exchange

Abstract: Despite the remarkable thermochemical accuracy of Kohn–Sham density‐functional theories with gradient corrections for exchange‐correlation [see, for example, A. D. Becke, J. Chem. Phys. 96, 2155 (1992)], we believe that further improvements are unlikely unless exact‐exchange information is considered. Arguments to support this view are presented, and a semiempirical exchange‐correlation functional containing local‐spin‐density, gradient, and exact‐exchange terms is tested on 56 atomization energies, 42 ionization potentials, 8 proton affinities, and 10 total atomic energies of first‐ and second‐row systems. This functional performs significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.

Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density

Abstract: A correlation-energy formula due to Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)], in which the correlation energy density is expressed in terms of the electron density and a Laplacian of the second-order Hartree-Fock density matrix, is restated as a formula involving the density and local kinetic-energy density. On insertion of gradient expansions for the local kinetic-energy density, density-functional formulas for the correlation energy and correlation potential are then obtained. Through numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, it is demonstrated that these formulas, like the original Colle-Salvetti formulas, give correlation energies within a few percent.

Self‐consistent molecular orbital methods. XXIII. A polarization‐type basis set for second‐row elements

Abstract: The 6‐31G* and 6‐31G** basis sets previously introduced for first‐row atoms have been extended through the second‐row of the periodic table. Equilibrium geometries for one‐heavy‐atom hydrides calculated for the two‐basis sets and using Hartree–Fock wave functions are in good agreement both with each other and with the experimental data. HF/6‐31G* structures, obtained for two‐heavy‐atom hydrides and for a variety of hypervalent second‐row molecules, are also in excellent accord with experimental equilibrium geometries. No large deviations between calculated and experimental single bond lengths have been noted, in contrast to previous work on analogous first‐row compounds, where limiting Hartree–Fock distances were in error by up to a tenth of an angstrom. Equilibrium geometries calculated at the HF/6‐31G level are consistently in better agreement with the experimental data than are those previously obtained using the simple split‐valance 3‐21G basis set for both normal‐ and hypervalent compounds. Normal‐mode vibrational frequencies derived from 6‐31G* level calculations are consistently larger than the corresponding experimental values, typically by 10%–15%; they are of much more uniform quality than those obtained from the 3‐21G basis set. Hydrogenation energies calculated for normal‐ and hypervalent compounds are in moderate accord with experimental data, although in some instances large errors appear. Calculated energies relating to the stabilities of single and multiple bonds are in much better accord with the experimental energy differences.

Mechanisms Controlling the Function and Life Span of the Corpus Luteum

Abstract: The primary function of the corpus luteum is secretion of the hormone progesterone, which is required for maintenance of normal pregnancy in mammals. The corpus luteum develops from residual follic...