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By the introduction of Rb+ with large ionic radius and rigid SiO 4 unit into borate, a noncentrosymmetric crystal, RbBSi 2 O 6 polymorph has been obtained. Its structure was determined by single crystal X-ray diffraction technique, and it can be described as a three dimensional (3D) framework constructed by the Si/BO 4 tetrahedra via corner-sharing O atoms, the Rb atoms reside in the tunnels and large cavities of the 3D framework. In addition, the optical properties of RbBSi 2 O 6 and CsBSi 2 O 6 , including IR spectra, UV–Vis–NIR diffuse reflectance spectra, have been reported in this work. Both RbBSi 2 O 6 and CsBSi 2 O 6 reveal short deep ultraviolet (UV) cutoff edges (below 180 nm and 185 nm, respectively), so they may have potential application in deep UV fields. Furthermore, the first-principle theoretical studies on band structure and density of states have also been performed for RbBSi 2 O 6. By the introduction of Rb+ with large ionic radius and rigid SiO 4 unit into borate, a noncentrosymmetric crystal, RbBSi 2 O 6 has been obtained. Its structure can be described as a three dimensional (3D) framework constructed by the Si/BO 4 tetrahedra via corner-sharing O atoms, the Rb atoms reside in the tunnels and large cavities of the 3D framework. Image 1 • Both RbBSi 2 O 6 and CsBSi 2 O 6 reveal short deep ultraviolet (UV) cutoff edges (below 180 nm and 185 nm, respectively), so they may have potential application in the deep ultraviolet areas. • IR spectra of RbBSi 2 O 6 and CsBSi 2 O 6 are measured for the first time. • Band structures and density of states have been calculated for RbBSi 2 O 6. [ABSTRACT FROM AUTHOR]

Quantum chemistry methods were used to calculate the energy parameters of an elementary unit and a cellulose macromolecule dimer (cellobiose), and structure simulation was performed and the energy of interaction between the fragments of native cellulose macromolecules was calculated. It was established that the trans conformation of cellobiose is more stable than the cis conformation by 6.7 kcal/mol. Differences in the calculated and real (according to literature data) IR spectra of cellulose were related to the presence of intramolecular and intermolecular hydrogen bonds in the native structure. It was shown that the interaction of individual fragments of cellulose macromolecules from eight monomer units is due to the manifestation of intramolecular hydrogen bonds. It was found that the energies of intermolecular interactions ∆Е essentially depend on the terminal groups X in the cellulose macromolecule fragments, and they are –26, 49, and ‒32 kcal/mol for X = –H, –COOH, and –COH, respectively. The structure of the interacting fragments of cellulose macromolecules can be regulated by replacing the hydrogen atoms of hydroxyl or terminal groups of the macromolecules with functional groups that do not form intramolecular hydrogen bonds and impede self-organization into fibrillar structures. It was shown that compounds with a high electron affinity or a negative energy of the lower vacant molecular orbital are the best reagents for complexation reactions with cellulose. [ABSTRACT FROM AUTHOR]

The electric field can change the absorption of fullerene C60 to different wavelengths of light by affecting the vibrational modes and electronic transitions. The IR spectrum of fullerene C60 under the strong electric field is studied on B3LYP/6-31G* basis set using density function theory. With the external electric field decreasing, silent modes Hg(1), Ag(1), Gu(2), Hg(5), Ag(2), Hu(7) become active. Meanwhile, UV-Vis spectrum, the excitation energy, excitation wavelength and oscillator strength of first fourteen excited states of fullerene C60 under the field are also studied in B3LYP/6-31G* basis set using time-dependent density functional theory. With the electric field increasing, the absorption peak of fullerene C60 occurs then shifts towards the long-wave region. The excitation energy decrease and the excitation wavelength increase correspondingly, and external electric field makes fullerene C60 absorb energy from 1.01 to 2.31 eV in theory. The energy gap decreases drastically from 2.74 to 1.38 eV, which contributed to tune the energy gap of fullerene C60 by the effect of the electric field in a wide range. It is possible to use electric field to tune fullerene C60 into new energy storage material. [ABSTRACT FROM AUTHOR]

The method is based on the thermodynamic parameters of the molecules- standard molar Gibbs free energy change of molecular formation ΔGf0 (kJ/mol), standard molar enthalpy change of molecular formation ΔHf0 (kJ/mol) and standard molar entropy of molecule S0 (J/mol·K). From these thermodynamics parameters the vibrational modes in infrared diapason can be calculated using TG=ΔGf0/S0 and TH=ΔHf0/S0 ratios, considered as ‘apparent’ temperatures. After conversion of the thermal energy kTG or kTH (k is Boltzmann constant) to energy of electromagnetic quanta E=hν (h is Planck constant), an frequencies in infrared spectral range are derived 1/λ=kTG/ch (cm-1), where λ= c/ν (c is speed of light). The calculated frequencies coincide with the vibrational mode on infrared spectrum of given corresponding molecule. The difference between the theoretically calculated frequencies and the experimentally measured ones in the infrared spectra of the studied molecules is within 50 cm-1.

Abstract Partial least squares-discriminant analysis (PLS-DA) is a favored modeling tool for high-dimensional data, e.g. infrared and Raman spectra. Prior to prediction, one needs to pre-select one decision rule (DR) for the PLS-DA model. The purpose of this work is to evaluate statistical differences of four novel DRs and the naïve DR in PLS2-DA prediction models for classification of blue gel pen inks based on attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra. The performances of the DRs have been estimated using forty sub-datasets that were prepared from the principal ATR-FTIR spectra. The global region together with three mutually exclusive spectral windows were preprocessed independently via nine different data preprocessing methods (i.e. mean centering, autoscaling, Pareto scaling, robust scaling, multiplicative scatter correction, normalization to sum, normalization to constant vector length, standard normal variate and asymmetric least squares). Then a series of 50 models (i.e. by including the first 50 PLS components incrementally) was constructed using the forty sub-datasets independently. Each model was evaluated using six different variants of v -fold cross-validation and external testing; and selected models were also assessed using iterative random sampling approach. Eventually, each DR was presented with a number of model estimates that describe the model accuracy and stability. Performances of the DRs were discussed according to summary statistics and ANOVA tests that were derived from the model estimates. Results show that the novel DRs are more accurate but relatively less stable than the naïve DR. The differences are statistically significant at the 0.05 significance level. In conclusion, both novel and naïve DRs are competitive with each other; and one has to decide on a trade-off between model stability and model accuracy. Highlights • The performances of different decision rules (DRs) in PLS2-DA modeling are explored using spectral data. • The difference between naïve DR and four novel DRs is assessed using ANOVA test. • Naïve DR underperforms novel DRs in terms of model accuracy. • Naïve DR outperforms novel DRs in terms of model stability. [ABSTRACT FROM AUTHOR]

The absorption of 1-butyl-3-methylimidazolium chloride and acetate taken from commercial packaging was studied by means of UV-VIS and infrared spectroscopy with some differences observed. Further research showed that heating both 1-butyl-3-methylimidazolium chloride and acetate alone, as well as in the presence of wood pulp, causes the darkening of these ionic liquids. Changes in the colour of ionic liquids associated with a variation in the absorption characteristics of pure ionic liquids and wood solutions in these liquids in UV and visible light are expressed primarily in the widening of the absorption bands. The presence of coloured products formed during their heating, as well as dissolution of the chemical components of wood in ionic liquids, had relatively little effect on the position of individual absorption bands in the spectrum obtained by the FT-IR method. The small differences in the absorption of spruce groundwood solutions in ionic liquids in IR as compared to pure ionic liquids suggest that strong chromophore groups in ionic liquids are created without serious reconstruction of their structure. [ABSTRACT FROM AUTHOR]

The chemical composition, crystal structure, and infrared (IR) spectrum of a hydrated CO3-bearing analog of manganoeudialyte from alkali pegmatites of the Konder pluton (Khabarovsk krai) are studied. The chemical composition of the mineral corresponds to the formula N[Na6.94H2O5.13(Y,REE)0.58. Pb0.31K0.28Ba0.08]13.32M1[Ca5.09Sr0.89]5.98M2[Mn1.523+Ti0.21Mg0.04Fe0.033+Al0.02]1.82M3(Si1.16Nb0.47)1.63 M4(Si)0.50. Z[Zr3.04Hf0.03]3.07(Si3O9)2(Si9O27)2(CO3)0.28 X[(H2O)4.45OH0.04Cl0.03]4.52. The IR spectrum contains the following lines (s, strong; sh, shoulder): 455s, 475s, 655, 740s, 925s, 977s, 1010s, 1145, 1420sh, 1504, 1650, 2970sh, 3240sh, 3480 cm-1. The crystal structure is refined in the R3¯m spatial group, a = 14.243(3), c = 30.371(6) Å, and V = 5336(2) Å for 1393 independent reflections (|Fo| > 4σF with a similarity factor R1 of 6.5%. The deficit in Na and Cl, the presence of Pb and Ba, and the high degree of hydration of the mineral indicates postcrystallization ion-exchange processes typical of hydrothermal alteration of aegirine-albite rocks of the Konder pluton. [ABSTRACT FROM AUTHOR]

Abstract In response to our review paper [L.C. Lee et al., Chemom. Intell. Lab. Systs. 163 (2017) 64–75], we present a study that explores practical impacts of data preprocessing (DP) methods in ATR-FTIR spectra. Nine common DP methods, i.e. mean centering (MC), autoscaling (AS), Pareto scaling, robust scaling, multiplicative scatter correction (MSC), normalization to sum (NS), normalization to constant vector length (NV), standard normal variate and asymmetric least squares (AsLS), were chosen on the sake of their availability in the R software and the rather simple computation steps. An ATR-FTIR spectral dataset of blue gel pen inks that is originated from 10 different manufacturers (i.e. brands) was used in this work. The dataset is colossal (N = 1361), high dimensional (J = 5401), multi-class (C = 10), and imbalanced. In order to examine the impacts of substrate interferences, the global spectral region was further divided, arbitrarily, into three mutually exclusive local regions and analyzed independently. Following that, the resulting four sub-datasets (i.e. one based on global and three based on local regions) were preprocessed via the DP methods independently to produce 40 different sub-datasets including the raw counterparts. Partial least squares-discriminant analysis (PLS-DA) was chosen to construct a series of 50 models by including the first 50 PLS components incrementally. The modeling was performed independently for each of the 40 sub-datasets. Each model was evaluated repeatedly using autoprediction, six variants of v -fold cross validation (v = 2, 4, 5, 7, 10, 15) and external testing schemes. As a results, empirical performances of each DP methods are represented by 400 different error rates (8 model validation schemes × 50 models). Performances of each DP method was then compared against its raw counterparts according to summary statistics and hypothesis tests. In addition, principal component analysis and hierarchical clustering analysis were also employed, respectively, to illustrate the spatial distribution and the similarity between the nine DP methods and the raw counterparts. Several important remarks have been drawn from the rigorous comparative analyses. First, due to the inherent properties of ATR-FTIR spectra, DP methods that handling slope, e.g. MSC and AsLS, have appeared to be the most excellent DP methods. Second, normalization methods, either NS or NV, ranked the second best-performing DP method. Third, MC shows no impact on the raw IR spectral dataset. Fourth, it is shown that outliers in the ATR-FTIR spectra of pen inks could be localized. Last but not least, removal of irrelevant signals arising from sample substrate is best achieved via region truncation rather than via PLS or DP methods alone. Highlights • ATR-FTIR spectra of pen inks is seriously overlapped with substrate interference. • ATR-FTIR spectra is best preprocessed via slope correcting algorithms. • Normalization methods are the second best-performing data preprocessing method. • Mean centering shows no effect on ATR-FTIR spectral dataset. • Outliers in the ATR-FTIR spectra of pen inks could be localized. [ABSTRACT FROM AUTHOR]

The title complex Cd/4-(phosphonomethyl) benzoic acid 4-HOOCC6H14CH2PO3(H3BCP) with 1,10-phenanthroline has been hydrothermally synthesized directly as [Cd3(BCP)2(phen)]·H2O 1 (phen = 1,10-phenanthroline). The crystal structure was determined by single-crystal X-ray diffraction with the following data: triclinic P-1. The complex is a two-dimensional layer structure. Interestingly, the one-dimensional cluster chain is composed of the novel repeated La4 cluster units connected by two Cd3 ions. The adjacent cluster chains link to be 2D layer structure by the coordination interaction of oxygen atoms of the carboxyl with the Cd3 ions of the adjacent chains. It is worthy of mentioning that IR, photo-luminescent and solid UV-Vis spectrum are employed in order to explore the structural characteristics. [ABSTRACT FROM AUTHOR]

Dioxin is a highly toxic and caustic substance, which widely existed in the atmosphere, soil and water with tiny particles. Dioxin pollution has become a major problem that concerns the survival of mankind, which must be strictly controlled. The bond length, bond angle, energy, dipole moment, orbital energy level distribution of dioxin under the external field are investigated using DFT (density functional theory) on basis set level of B3LYP/6-31G (d, p). The results indicate that with the increase of the electric field, the length of one Carbon-Oxygen bond increases while another Carbon-Oxygen bond decreases. The energy gradually decreases with the electric field, while the change of the dipole moment has an opposite trend. In the infrared spectra, the vibration frequency decreases with the electric field increasing and shows an obvious red shift. Moreover, the ultraviolet-visible absorption spectra under different electric fields are analyzed with TD-DFT (time-dependent density functional theory) method. The wavelength of the strongest absorption peak increases and occurs red shift with the increase of the electric field. All the above results can provide reference for further research on the properties of dioxin under different external electric field. [ABSTRACT FROM AUTHOR]

Diesel fuel from Azerbaijan oils was studied using chromatography and IR spectroscopy. The concentrations and radiation-chemical yields of gases after irradiation of samples were established. Their radiation resistance was evaluated. Radiation effects on the operating characteristics of diesel fuel under static conditions before and after irradiation were investigated. [ABSTRACT FROM AUTHOR]

Chlorobenzene is one of the Persistent Organic Pollutants (POPs) threatening human health. It is significant to study the degradation mechanism under external electric fields. Based on the density functional theory, the physical and dissociation properties including C-Cl bond length, total energy, dipole moment, frontier orbital energy, energy gap, IR spectrum, UV-vis absorption spectrum and potential energy curve are studied under external electric fields. According to these results, it is found that the C-Cl bond length becomes longer and tends to break with the increase of external electric field and the energy gap decreases with the increase of positive as well as negative external electric field. Moreover, the dissociation barrier in potential energy curve decreases and equilibrium bond length increases with increase of positive external electric field. And when external electric field reaches 0.040 atomic units (, 1 atomic , the dissociation barrier disappears which means that degradation of chlorobenzene occurs under strong external electric field due to the breakage of C-Cl bond. These results provide important references for studying the degradation mechanism of chlorobenzene under strong external electric fields. [ABSTRACT FROM AUTHOR]

External testing (ET), known also as the hold-out validation, is currently considered to be one of the most reliable ways to estimate predictive ability of a statistical model. One safeguard to prevent impermissible peeking in ET is to ensure all replicates of a particular sample is only included in either the test or the training set. Assuming a sample X1 consists of two replicates (i.e. X1a and X1b). The model is claimed to enjoy impermissible peeking if the X1a and X1b are split into the training and the test sets, respectively. Eventually, the resulting prediction model is expected to predict the test sets easily and presents an over-optimistic model performance. In forensic document examinations, an individual pen (IP) can be used to produce multiple ink strokes. In real-world practice, pens are manufactured via bulk production such that one big tank of ink is used to produce a wealth of IPs. In other words, ink strokes produced by varying IPs but of the same pen model are indeed originated from one single source (i.e. the same tank of ink). Eventually, with respect to the aforementioned safeguard, how shall one treat the ink strokes? Are they replicates or independent samples? In this context, the aim of the work is to investigate the validity of the safeguard in splitting dataset for hold-out validation strategy (i.e. ET) in the domain of forensic pen ink analysis. An infrared (IR) spectra of blue gel pen inks was used to demonstrate the practical aspect. The IR spectral data were collected from 1361 ink strokes that originated from 273 IPs of 23 pen models and 10 pen brands. Iterative stratified random sampling was employed to prepare 1000 pairs of training and test sets that were split at ratio 7:3 using two different principles: (a) set IP - selection was conducted at IP level to ensure all the ink strokes originated from a particular IP must be included into either the training or the test sets only; and (b) set NIP - ink strokes of a particular IP were allowed to be spread between the training and the test sets. For each dataset, a series of 50 PLS-DA models were constructed by including the first 50 PLS components incrementally, which were then validated via auto-prediction and ET. Following that, the performances between IP and NIP model series were compared with respect to: (a) model accuracy; (b) model stability; and (c) model fitting. In conclusion, the NIP model series do not show any evidence of advantages from the impermissible peeking since both the NIP and IP model series exhibit quite similar performances in all the three model aspects. [ABSTRACT FROM AUTHOR]

The rate constants of OH radicals with CF3CF=CCl2, CF3CH=CF2, CF3CF=CH2, CF3CH=CH2, and (CF3)2C=CH2 have been measured over the temperature range 250-430 K. Kinetic measurements have been carried out using flash photolysis and laser photolysis methods combined respectively with laser-induced fluorescence technique. The Arrhenius rate parameters have been determined as k(CF3CF=CCl2) = (6.50 ± 0.22) × 10−13∙exp[(200 ± 10)/T], k(CF3CH=CF2) = (4.85 ± 0.14) × 10−13∙exp[(120 ± 10)/T], k(CF3CF=CH2) = (1.54 ± 0.03) × 10−12∙exp[− (100 ± 10)/T], k(CF3CH=CH2) = (1.06 ± 0.02) × 10−12∙exp[(80 ± 10)/T], and k((CF3)2C=CH2) = (8.75 ± 0.23) × 10−13∙exp[− (20 ± 10)/T] cm3 molecule−1 s−1. Infrared absorption spectra of the halogenated alkenes have been measured at room temperature. The atmospheric lifetime, global warming potential, ozone depleting potential, and photochemical ozone creation potential have been estimated. The change in the reactivity of halogenated alkenes by the substitution has been examined by considering the structure containing the atoms or atomic groups attached to the carbons on both sides of the double bond. [ABSTRACT FROM AUTHOR]

The structure of levofloxacinium 2-thiobarbiturate trihydrate LevoH2+Htba-·3H2O (I) (LevoH is levofloxacin, H2tba is 2-thiobarbituric acid) is determined (CIF file CCDC No. 1547466); its thermal decomposition and IR spectrum are studied. The crystals of I are triclinic: a = 8.670(1) Å, b = 9.605(1) Å, c = 15.786(2) Å, α = 89.144(5)°, β = 88.279(5)°, γ = 76.068(5)°, V = 1275.4(3) Å3, space group P1, Z = 2. The unit cell of I contains two LevoH2+ ions, two Htba- ions, and six H2O molecules. The absolute structure of the crystal and the configuration of the chiral center in a levofloxacin molecule S are determined. Experiments for generating the second optical harmonics gave a positive result. Intermolecular hydrogen bonds (HBs) N-H···O and O-H···O in I form a bilayer system along the ab diagonal with hydrophilic moieties within a layer and hydrophobic moieties directed outward. The structure is stabilized by multiple HBs and the π-π interaction between the Htba-and LevoH2+ ions and between the LevoH2+ ions. [ABSTRACT FROM AUTHOR]

The complex (2,2′‐biquinoline‐κ2N,N′)(carbamoylcyanonitrosomethanide‐κ2N,O)chloridocopper(II) acetonitrile monosolvate, [Cu(C3H2N3O2)Cl(C18H12N2)]·CH3CN or [Cu(ccnm)Cl(biq)]·acn (acn is acetonitrile, biq is 2,2′‐biquinoline and ccnm is carbamoylcyanonitrosomethanide), (I), was prepared as a result of nucleophilic addition of water to the dicyanonitrosomethanide ion in the presence of CuII and biq. IR spectroscopy confirmed the presence of ccnm, biq and acn in (I). The solid‐state structure consists of the neutral complex containing ccnm and biq ligands, coordinated to the CuII atom in a bidendate chelating manner, and a chloride ligand, resulting in a distorted tetragonal pyramidal coordination of CuII. The asymmetric unit is supplemented by one molecule of solvated acn which, along with the nitrile group of ccnm, serves as an acceptor in intermolecular hydrogen bonding, creating infinite chains along the b axis. Magnetic measurements revealed a paramagnetic behaviour with a very small Weiss temperature Θ = −0.32 K and high anisotropy of the g tensor (gx = 2.036, gy = 2.120 and gz = 2.205). [ABSTRACT FROM AUTHOR]

The ν(OH) stretching-mode bands in solution IR spectra of five o-vinylphenol (o-VPh) homologs in the slightly polar solvents CCl4 and n-hexane were studied. Several rotamers with free OH groups were found in solutions of o-VPh and its methyl-substituted derivatives in n-hexane. The proportion of rotamers in o-VPh homologs with intramolecular hydrogen bonds (IHBs) O-H...π varied from 22 to 97% in the gas and cyclohexane according to B3LYP/cc-pVTZ calculations. The theoretically estimated effective enthalpies -ΔH of their IHBs varied in the range 0.20-2.24 kcal/mol. [ABSTRACT FROM AUTHOR]

The influences of the structure of the anionic axial ligands in Group-IIIA and -IVA metal-phthalocyanine complexes and intermolecular interactions on the absorption spectra of the macroheterocycles in solutions, an organic polymer, and nanoporous silicate gel matrices were studied. It was shown that anionic Cl - ligands of the central metal ion were effectively substituted for hydroxyls (OH -) during the synthesis and purification of the metallophthalocyanines. Studies of solid-state nanoporous samples obtained by the sol-gel method showed that activator hydroxoaluminumphthalocyanine molecules were incorporated as monomers into the organo-inorganic silicate material. The optically homogeneous luminescent xerogel could be used in optical devices for the wavelength range adjacent to the near-IR region. [ABSTRACT FROM AUTHOR]

An improved procedure for isolation of 5-amino-3-methyl-1,2,4-thiadiazole in pure form on a multi-gram scale without chromatography is reported. Its 1H and 13C-NMR and IR data are presented and previously published erroneous data corrected. The molecular structure is confirmed by X-ray diffraction which shows layers consisting of an elaborate two-dimensional hydrogen bonded network of molecules. [ABSTRACT FROM AUTHOR]

Hybrid B3LYP and gradient SLYP functionals were used to reveal the structure of organic mass of coal within the density functional theory in the basis of local orbitals. For all modeled compounds a number of important characteristics was identified – the lengths of bonds and angles. The IR spectra, the values of total energy and reactivity parameters, allowing for comparison with experimental data were calculated.

The development of an effective and mechanically robust organogel coating that is both superoleophilic and under-oil superhydrophobic is presented. The organogel was shown to absorb and retain oil, and as a consequence render the surface superhydrophobic. The coating showed high repellence against water while letting oil pass through without the need to apply pressure. Utilization of the coating in oil and water separation was investigated and exhibited ≥ 99% separation efficiency for a wide variety of commercial oil. The coating was also shown to be mechanically robust and can withstand shear tests of different strengths and duration. [ABSTRACT FROM AUTHOR]

The experimental infrared (IR) spectrum of composite wax powder was investigated. The frequency shifts of the C=C anti-symmetrical stretching mode were observed and the experimental cooperativity effect involving Na+···π interaction was suggested. In order to further reveal the nature of cooperativity effect, the interaction energies in Mn+···coronene···CH4(Mn+= Li+, Na+, K+, Be2+, Mg2+or Ca2+) as the model systems of composite wax powder were calculated by using the B3LYP, M06-2X and MP2 methods with 6-311++G**basis set. The results show that the Mn+···π interactions were strengthened upon the formation of ternary complexes. Although the changes of absolute values of the interactions between CH4and coronene were not obvious, the relative values were considerably significant upon the formation of ternary complexes. The cooperativity effect was perhaps the reason for the formation of notable advantage of composite wax powder upon the introduction of surfactant with cation into wax powder. Reduced density gradient and atoms-in-molecules analysis confirm the cooperativity effect in Mn+···coronene···CH4, and reveal the nature of the formation of the predominant advantage of composite wax powder. [ABSTRACT FROM PUBLISHER]

A new method for calculating vibrational modes in the infrared region of the spectrum is proposed. The method is based on the thermodynamic parameters of the molecules-standard molar Gibbs free energy change of molecular formation ΔGf0 (kJ/mol), standard molar enthalpy change of molecular formation ΔHf0 (kJ/mol) and standard molar entropy of molecule S0 (J/mol·K). From these thermodynamics parameters the vibrational modes can be calculated using TG= ΔGf0/S0 and TH = ΔHf0/S0 (in K) as 'apparent' temperatures. After equation of thermal energy kTG and kTH (where k is Boltzmann constant) to energy of electromagnetic quanta hfG and hfH (where f is frequency in Hz), it can calculate the wavenumbers (in cm-1) of vibrational modes as: kTG/ch and kTH/ch (where c is the speed of light and h is the Planck constant). [ABSTRACT FROM AUTHOR]

Agardite-(Ce) from Clara Mine, Schwarzwald, Germany, has been investigated by means of electron microprobe analysis, single-crystal X-ray analysis, XANES spectroscopy and IR spectroscopy. Hexagonal unit-cell parameters are: a = 13.598(6), c = 5.954(3) Å; V = 953.5(2) Å3; space group P63/m. The structure has been solved and refined to final R1 = 3.87%, wR2 = 5.02 for 786 I > 3σ(I). Hydrogen atoms have been localized. The crystal-chemical formula is (Z = 2): A(1)(Ce0.82Ca0.14Sr0.04)Σ1.00A(2)(Ca0.03Ce0.02)Σ0.05 [Cu5.75(Fe3+, Mn)0.20]Σ5.95 [T(1)(AsO4)2.96T(2)(SbO4)0.04)]Σ3.00 (OH)5.96O0.04·3H2O. Hydrogen bonding in agardite-series minerals has been characterized for the first time. IR spectra of agardite-(Ce) and agardite-(Nd) from Lavrion used for comparison, as well as structural data indicate the presence of isolated H+ cations that do not form strong covalent bonds with coordinating O atoms. Agardite-(Ce) from Clara Mine forms epitaxial growths with the Sb-analogue of auriacusite. The latter mineral was characterized by EDS analyses; its typical empirical formulae are Ca0.06Ce0.04Fe3+1.06Cu0.89[(SbO4)0.58(AsO4)0.38(SiO4)0.04]Σ1.00(O,OH) and Ca0.075Ce0.04Fe3+0.93Cu0.97[(SbO4)0.59(AsO4)0.35(SiO4)0.06]Σ1.00(O,OH). The formation of uniaxial growths of the Sb-analogue of auriacusite and agardite-(Ce) is caused by the close values of their c parameters (for auriacusite s.s. c  =  5.9501(5) Å). Three-valence state of iron and five-valence of antimony in both minerals has been validated by means of Fe K- and Sb L2,3-edge XANES spectroscopy. [ABSTRACT FROM AUTHOR]

Sideridiol ( ent-7α,18β-dihydroxykaur-15-ene) one of the ent-kaurene diterpenoid, is isolated from the genus Sideritis L. belongs to the family of Lamiaceae. The vibrational frequencies of sideridiol in the ground state have been calculated using the Density Functional Theory (DFT) method with the 6-31G( d) and 6 31+G( d, p) basis sets. The calculated vibrational frequencies have been compared with that of obtained experimental IR spectrum. [ABSTRACT FROM AUTHOR]

Crystal structure of orthorhombic γ-CdC 2 O 4 (sp.gr. Pmna , a = 7.3217(1), b = 6.0231(1), c = 9.2545(2) Å, V = 408.12(1) Å 3 , Z = 8, D x = 3.262 Μg·m −3 ) was solved from the powder diffraction pattern. Each metal atom in the structure is co-ordinated by seven oxygen atoms which belong to five oxalate-ions. Crystal packing containing the noticeable cavities in the [101] and [001] directions is not close and essentially differs from the known disordered α- and ordered β-modifications of transition metal oxalates. This modification seems to be meta-stable. It was found that spontaneous γ→β phase transition takes place for the γ-CdC 2 O 4 aged during 6 month in air. This transition may be accelerated via the heating of γ-CdC 2 O 4 with excessive amounts of oxalic acid. [ABSTRACT FROM AUTHOR]

The interaction of the functional groups in the polyurethane foam adsorbent Penopurm with the cations of some 3d-metals upon their extraction from aqueous solutions has been studied by atomic emission spectroscopy, UV/Vis and vibrational IR spectroscopy, and quantum chemical simulation using density functional theory. Penopurm absorbs 3d-metal cations from aqueous solutions in the pH range 5-7. Some spectral criteria have been found indicating a predominant interaction of Ni ions with various fragments of the polyurethane foam structure. [ABSTRACT FROM AUTHOR]

Two new metal-organic frameworks (MOFs) based on cadmium(II) ions, 1,2-benzenedicarboxylic acid (BDC), flexible ligand 1,4-bi(1H-imidazol-1-yl)butane (BIIM), coordinated water molecules, [(BIIM)(BDC)(HO)Cd] ( 1) and copper(II) ions, BIIM, coordinated water, free thiophene-2,5-dicarboxylate (TDC), free water, {[(BIIM)(HO)Cu]·(TDC)·(HO)} ( 2) are prepared and characterized by X-ray diffraction, thermal gravimetric analysis (TGA), infrared (IR) spectrum and the photoluminescence property for complex ( 1). The X-ray diffraction analysis reveals that the structures of complexes 1 and 2 are 2D structures through the C-H···π stacking interactions (for 1) and the BIIM bridging connections (for 2). The IR spectrum for 1 and 2 are presented in the paper, for 1, the strong peaks at 1399 and 1573 cm are owing to the carboxylic CO symmetry and asymmetry stretching vibrations of BDC. The features of the IR spectrum are consistent with the single crystal structures. The TGA reveal the water is the first lost material from complex, then the ligands removed, and finally the residues of these two complexes are the metal oxide. [ABSTRACT FROM AUTHOR]

Electronic structure of para-methoxybenzylidine p -ethylaniline (MBEA), a pure nematic liquid crystal has been examined using ab–initio, HF/6-31G(d,p) and DFT B3LYP/6-31G(d,p) techniques with GAMESS program. MBEA transforms from crystal to nematic at 28 °C and nematic to isotropic phase at 57 °C. Potential Energy Surface (PES) in terms of various conformations and charge distribution analysis have been carried out. Molecular Electrostatic Potential (MEP), Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) surfaces have been scanned. Ionization potential, electron affinity, electronegativity, global hardness and softness parameters of the liquid crystal molecule have been determined. Molecular and thermodynamic properties such as total energy, dipole moment, entropy, enthalpy and Gibbs free energy have been calculated at 298.15 K temperature. FTIR showed that calculated and experimental frequencies are in agreement. Stacking, side by side and end to end interactions between a molecular pair have been evaluated employing modified second order perturbation theory along with multicentred-multipole expansion technique. Results have been used to elucidate the physico-chemical and liquid crystalline properties of the system. [ABSTRACT FROM AUTHOR]

A procedure based on density functional theory is proposed for calculation of Au(ХCH) (Х = S, Se, Te) isomers. It is established that the most stable isomer for all X has a core-shell structure: Au@(AuXCH)(XCH(AuXCH))(XCHAuXCH). Optical and IR spectra, ionization potential, and electron affinity are calculated for the first time for all clusters. It is shown that a cluster protected by thiolate ligands has the greatest electronic and thermodynamic stability. [ABSTRACT FROM AUTHOR]

Post-combustion carbon capture using membranes is a key approach to control CO 2 emissions from power plants using fossil fuels. The minor contaminants, such as SO 2 and O 2 , may influence the long-term membrane performance. With the presence of SO 2 in the feed gas, SO 2 could preferably react with amine carriers and hinder the permeation of CO 2 in the amine-containing facilitated transport membranes. Possible amine degradation and competitive reactions would reduce membrane performance with real flue gas. With SO 2 concentrations of 0.7–5 ppm, two amine-containing facilitated transport membranes were tested at 57 and 102 °C, respectively. Unstable membrane performance was observed at 102 °C for the membrane containing Lupamin® as fixed-site carrier and potassium glycinate (K-Gly) as mobile carrier in the presence of SO 2 . On the contrary, two membranes containing polyvinylamine (PVAm) as fixed-site carrier and amino acid salts as mobile carriers showed stable separation performance in the presence of 1–3 ppm SO 2 at 57 °C. Therefore, the operating temperature plays a significant role in the membrane stabilities in the presence of SO 2 . In addition, the infrared (IR) spectra of the membrane components exposed to SO 2 with respect to exposure time were collected. It was found that the amines reacted with SO 2 to form sulfite products irreversibly at 102 °C. The spectral results were consistent with the observed membrane separation performance. The stable membrane performances of the facilitated transport membranes at 57 °C with SO 2 at ppm levels indicate the applicability of the developed amine-containing membranes for use in CO 2 capture from real flue gas. [ABSTRACT FROM AUTHOR]

In this work, the title molecule, 7-Methyl-3-[(3-methyl-3-mesityl-cyclobutyl]-5-phenyl-5 H -thiazolo[3,2-α]pyrimidine-6-carboxylic acid ethyl ester (C 30 H 34 N 2 O 2 S 1 ), was synthesized and characterized by FT-IR spectroscopy and single crystal X-ray diffraction. The compound crystallizes in the triclinic space group P 2 1 / c . with Z = 4, a = 14.1988(6), b = 19.0893(5), c = 10.1325(4) Å, V = 2674.56(17) A 3 . The optimized structure parameters of the studied molecule was determined theoretically using HF/6-31G(d) and B3LYP/6-31G(d) methods for ground state, and compared with previously reported experimental findings. The calculated harmonic vibrational frequencies are scaled and they are compared with experimental frequencies obtained by FT-IR spectra. The electronic properties, such as HOMO and LUMO energies, and molecular electrostatic potential (MEP) are also performed. [ABSTRACT FROM AUTHOR]

FTIR spectroscopy is a powerful method to analyse materials and especially fiber structure. This technique is largely used to obtain quick information on the fiber composition and to detect possible transformations after physical and chemical treatments. Unlike other techniques, FTIR is a quick method which demands a reduced amount of fibers. Furthermore, it is a non destructive method especially for Attenuated Total Reflectance (ATR), and Near Infrared (NIR) spectroscopy which are nowadays widely used. In this work, FTIR spectrum of agave fiber has been thoroughly investigated. Because of its complexity, the spectrum was separated into two regions: CH and hydrogen bond stretching (>2500 cm −1 ) and “fingerprint” region (<2000 cm −1 ). A detailed study of intermolecular and intramolecular chains was made. Infrared ratios (Lateral Order Index, Total Crystallinity Index, and Hydrogen Bond Intensity) were used to study the crystallinity and the degree of regularity of agave fiber. [ABSTRACT FROM AUTHOR]

The structure (CIF file CCDC No. 1401886) of the hexaaqua- hexakis(2-thiobarbiturato)-disamarium [Sm(HO)(HTBA)] polymeric complex ( I), where HТВА is 2-thiobarbituric acid, is determined; its thermal decomposition and IR spectrum are studied. The crystals of I are monoclinic: a = 14.072(1) Å, b = 10.0842(6) Å, c = 15.323(1) Å, β = 110.408(2)°, V = 2037.9(2) Å, space group P2/ n, Z = 2. All three independent thiobarbiturate anions HTBA coordinate to Sm through oxygen atoms. To one of independent Sm ions six (two terminal and four bridging) HTBA ions and two water molecules are coordinated; the second is bonded with four bridging HTBA and four water molecules, forming square antiprisms. The bridging HТВА-anions arrange antiprisms in layers. The structure is stabilized by hydrogen bonds and a π-π interaction between the HТВА ions. The topology of the polymer network of I is analyzed. [ABSTRACT FROM AUTHOR]

ATR-FTIR spectroscopy in the combination with chemometrics has been practiced over the past decades. Works presented in numerous disciplines provide ample empirical evidence in support for the coupling relationship. However, Data Pre-processing (DP) which constitutes the first step in chemometric analysis pipelines, is seldom given reasonable attentions. The aim of this paper is two-fold: (a) to review contemporary DP practice strategy by ATR-FTIR user, and (b) to critically discuss the rationales that could have been nurturing such practices. In the first part, basic concepts of chemometrics and ATR-FTIR spectroscopy are described. Then, the status quo of DP practice strategy is outlined and critically discussed on whether the contemporary practice has been malpractice or best practice. Finally, rationales that could have possibly contributed to some of the malpractices are discussed. [ABSTRACT FROM AUTHOR]

Density functional theory based calculations were performed to study vibrational properties of ceria, titania, and ceria-titania hybrid clusters. The findings revealed the dominance of vibrations related to oxygen when compared to those of metallic atoms in the clusters. In case of hybrid cluster, the softening of normal modes related to exterior oxygen atoms in ceria and softening/hardening of high/low frequency modes related to titania dimmers are observed. The results calculated for monomers conform to symmetry predictions according to which three IR and three Raman active modes were detected for TiO, whereas two IR active and one Raman active modes were observed for CeO. The comparative analysis indicates that the hybrid cluster CeTiO contains simultaneous vibrational fingerprints of the component dimmers. The symmetry, nature of vibrations, IR and Raman activity, intensities, and atomic involvement in different modes of the clusters are described in detail. The study points to engineering of CeTiO to tailor its properties for technological visible region applications in photocatalytic and electrochemical devices. [ABSTRACT FROM AUTHOR]