A combined experimental and density functional theory investigation of the hydrogen bonding of 2-cyclohexen-1-one and 3-methyl- 2-cyclohexen-1-one in solvents.

Hydrogen bonding is a weak chemical interaction widely existed in the variety of organic and biological molecules. As an important structural motif of pyrimidine bases, the solvent effect of the hydrogen bonding of 2-cyclohexen-1-one (CHO) and 3-methyl- 2-cyclohexen-1-one (3MCHO) and its effect on the frequency shift of the CO stretching mode were investigated by using the FT-Raman and UV absorption spectra and density functional theory calculations. The electronic transitions associated with the UV absorptions in different solvents were calculated at B3LYP-TD/6-31++G(d,p) level of theory and employing SCIPCM solvent model. The vibrational spectra of CHO and 3MCHO were assigned on the basis of the FT-Raman spectra in neat liquid and different solvents, the calculated vibrational spectra of monomer and CHO dimers, and the concentration dependent experiments of the band pair intensities. Hydrogen bonding energies of CHO-(H2O)n (n = 1,2) clusters were predicted. The results reveal that the CHO-(H2O)2 cluster and CHO monomer are respectively the major source of spectral observation in water and cyclohexane, while CHO dimmer and CHO monomer coexist in acetonitrile. The difference in the frequency of the νC=O stretching mode between 3MCHO monomer and CHO monomer in cyclohexane were explored.

[Clinical features of advanced adenoid cystic carcinoma in the nasal cavity and paranasal sinuses: analysis of 21 cases].

OBJECTIVE: To evaluate the clinical characteristics, treatment and prognosis of advanced adenoid cystic carcinoma (ACC) in the nasal cavity and paranasal sinuses. METHODS: Twenty-one patients with advanced ACC in the nasal cavity and paranasal sinuses were treated in our department between February, 2007 and May, 2016. The clinical manifestations, T-stage, N-status, treatment, histological grade, recurrence and distant metastasis of the tumors were analyzed. Univariate survival analysis was performed with Kaplan-Meier method and Log-rank test, and the factors affecting the prognosis of the patients were explored using multivariate analysis with Cox proportional hazard model. RESULTS: Among the 21 patients, 10 (47.6%) had ACC containing less than 30% of solid tumor tissues and their overall survival rates at 1, 3, and 5 years were 100%, 100% and 70%, respectively; in the 11 cases (52.4%) with solid tumor tissues no less than 30%, the overall survival rates at 1, 3, and 5 years were 70%, 40% and 10%, respectively, showing significant differences between the two groups (P=0.02). The Log-rank test and survival analysis using the covariate variable model curve indicated a significant impact of the pathological classification on the patients' prognosis. The patients in T3 stage had slightly better prognosis than those in T4 stage; tumors originating from the maxillary sinus had a slightly better prognosis than those from the sphenoid sinus. Surgery combined with radiotherapy resulted in better outcomes of the patients than surgery or radiotherapy alone. Multiariable Cox regression model analysis showed that the pathological classification (P=0.045) and the disease course (P=0.028) were closely related with the prognosis of the patients. CONCLUSION: ACC in the nasal cavity and paranasal sinuses has a low incidence without specific symptoms. Its early diagnosis can be difficult, and most of the patients are in advanced stage upon diagnosis. We recommend comprehensive treatments combining surgery, postoperative radiotherapy and chemotherapy for these patients. The pathological classification, disease course, lesion site, clinical stage, treatment approache, compromise of the peripheral nerves, status at the edge of resection, and postoperative radiotherapy dose can all be factors affecting the prognosis of patients with advanced ACC.

Utilization of Zn-containing electric arc furnace dust for multi-metal doped ferrite with enhanced magnetic property: From hazardous solid waste to green product.

One-step solid state reaction method was proposed for the first time to realize the transformation of the Zn-containing EAFD from hazardous solid waste to multi-metal doped ferrite with enhanced magnetic property. The effect of Zn-containing EAFD to NiCl2·6H2O mass ratio (RZE/N, g·g-1) on the phases transformation was investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Raman spectroscopy. The as-synthesized samples were treated by toxicity characteristic leaching procedure (TCLP). It is shown that the TCPL played a key role in determining both the purity and toxicity of the obtained ferrites. The pure metal doped Ni-Zn ferrite with higher saturation magnetization (Ms, 56.8 emu·g-1) and lower coercivity (Hc, 58.5Oe) was gained under the optimum conditions. And the pure ferrite was a green product according to the TCLP and EN12457 standards. Moreover, the evaluation of environmental impact and the recovery ratio of the dust were also discussed.

Excited state structures and decay dynamics of 1,3-dimethyluracils in solutions: resonance Raman and quantum mechanical calculation study.

The resonance Raman spectroscopic study of the excited state structural dynamics of 1,3-dimethyluracil (DMU), 5-bromo-1,3-dimethyluracil (5BrDMU), uracil, and thymine in water and acetonitrile were reported. Density functional theory calculations were carried out to help elucidate the ultraviolet electronic transitions associated with the A-, and B-band absorptions and the vibrational assignments of the resonance Raman spectra. The effect of the methylation at N1, N3 and C5 sites of pyrimidine ring on the structural dynamics of uracils in different solvents were explored on the basis of the resonance Raman intensity patterns. The relative resonance Raman intensities of DMU and 5BrDMU are computed at the B3LYP-TD level. Huge discrepancies between the experimental resonance Raman intensities and the B3LYP-TD predicted ones were observed. The underlying mechanism was briefly discussed. The decay channel through the S1((1)nπ*)/S2((1)ππ*) conical intersection and the S1((1)nπ*)/T1((3)ππ*) intersystem crossing were revealed by using the CASSCF(8,7)/6-31G(d) level of theory calculations.

Resonance Raman and density functional study of the excited state structural dynamics of 3-amino-2-cyclohexen-1-one in water and acetonitrile solvents.

FT-Raman and/or FT-IR spectra of 3-amino-2-cyclohexen-1-one (ACyO) in solid state and/or in solvents of water and acetonitrile were obtained. Density functional theory calculations were done to help elucidate the vibrational band assignments. The A-band resonance Raman spectra of ACyO were acquired in water and acetonitrile solvents to examine the excited state structural dynamics and the state-mixing or curve-crossing tuned by solvents. A preliminary resonance Raman intensity analysis using the time-dependent wave-packet theory and simple model was done for ACyO in acetonitrile solvent. Resonance Raman spectroscopic probing of the excited state curve-crossing or state-mixing was proposed.

Resonance Raman spectroscopic and theoretical investigation of the excited state proton transfer reaction dynamics of 2-thiopyridone.

The resonance Raman spectra were obtained for both 2-thiopyridone (2TP) and its proton-transfer tautomer 2-mercaptopyridine (2MP) in water solution. Density functional theory (DFT) calculations were carried out to help elucidate their ultraviolet electronic transitions and vibrational assignments of the resonance Raman spectra associated with their B-band absorptions. The nanosecond time-resolved resonance Raman spectroscopic experiment was carried out to further confirm the assignment that the transient species was the ground state 2MP. The different short-time structural dynamics were examined for both 2TP and 2MP in terms of their resonance Raman intensity patterns. The transition barriers between 2TP and 2MP for S(0), T(1), and S(1) states are determined by using (U)B3LYP-TD and CASSCF level of theory computations, respectively. The excited state proton transfer (ESPT) reaction mechanism is proposed and briefly discussed.

A resonance Raman spectroscopic and CASSCF investigation of the Franck-Condon region structural dynamics and conical intersections of thiophene.

Resonance Raman spectra were acquired for thiophene in cyclohexane solution with 239.5 and 266 nm excitation wavelengths that were in resonance with ∼240 nm first intense absorption band. The spectra indicate that the Franck-Condon region photodissociation dynamics have multidimensional character with motion mostly along the reaction coordinates of six totally symmetry modes and three nontotally symmetry modes. The appearance of the nontotally symmetry modes, the C-S antisymmetry stretch +C-C=C bend mode ν(21)(B(2)) at 754 cm(-1) and the H(7)C(3)-C(4)H(8) twist ν(9)(A(2)) at 906 cm(-1), suggests the existence of two different types of vibronic-couplings or curve-crossings among the excited states in the Franck-Condon region. The electronic transition energies, the excited state structures, and the conical intersection points (1)B(1)/(1)A(1) and (1)B(2)/(1)A(1) between 2 (1)A(1) and 1 (1)B(2) or 1 (1)B(1) potential energy surfaces of thiophene were determined by using complete active space self-consistent field theory computations. These computational results were correlated with the Franck-Condon region structural dynamics of thiophene. The ring opening photodissociation reaction pathway through cleavage of one of the C-S bonds and via the conical intersection point (1)B(1)/(1)A(1) was revealed to be the predominant ultrafast reaction channel for thiophene in the lowest singlet excited state potential energy hypersurface, while the internal conversion pathway via the conical intersection point (1)B(2)/(1)A(1) was found to be the minor decay channel in the lowest singlet excited state potential energy hypersurface.

Resonance Raman study of the A-band short-time photodissociation dynamics of 2,5-di-iodothiophene.

Resonance Raman spectra were obtained for 2,5-di-iodothiophene in cyclohexane solution with excitation wavelengths in resonance with its A-band absorption. These spectra indicate that the Franck-Condon region photodissociation dynamics have multidimensional character with motion mostly along the nominal symmetric C(2)C(3)C(4)C(5) stretch nu(2) (1388 cm(-1)) of the thienyl ring and this is accompanied by motions along the nominal symmetric CSC stretch nu(6) (640 cm(-1)), the nominal symmetric C[Single Bond]I stretch nu(7) (187 cm(-1)), the nominal antisymmetric CSC stretch nu(19) (728 cm(-1)), the nominal antisymmetric C(2)C(3)C(4)C(5) stretch nu(16) (1497 cm(-1)), the nominal C(3)C(4) stretch nu(3) (1286 cm(-1)) and four other vibrational modes. A preliminary resonance Raman intensity analysis was done and the results for 2,5-di-iodothiophene were compared to previous results for 2-iodothiophene and di-iodomethane to discuss the mechanism of the symmetric breaking in the initial A-band photodissociation dynamics of 2,5-di-iodothiophene and 2-iodothiophene.

Role of ribose in the initial excited state structural dynamics of thymidine in water solution: a resonance Raman and density functional theory investigation.

Resonance Raman spectra were obtained for thymidine and thymine with excitation wavelengths in resonance with the approximately 260 nm band absorption spectrum. The spectra indicate that the Franck-Condon (FC) region photodissociation dynamics of thymidine have multidimensional character with motion predominantly along the nominal C5=C6 stretch + C6-H bend nu17 (delta = 0.75, lambda = 468 cm(-1)), the nominal thymine ring stretch + C6-H bend + N1-C1, stretch nu29 (delta = 0.73, lambda = 363 cm(-1)), the nominal thymine ring stretch + C5-CH3/ N1-C1, stretch nu37 (delta = 0.69, lambda = 292 cm(-1)), and accompanied by the moderate and minor changes in the nu40, nu20 and nu23, nu55, nu60, nu61, nu63 modes. A preliminary resonance Raman intensity analysis was done, and these results for thymidine and thymine were compared to each other. The roles of ribose in the FC structure dynamics of thymidine were explored and the results were used to correlate to its lifetime constants tau1 and tau2 for two nonradiative decay channels. Spi/Sn conical intersection versus a distorted structure of Spi,min in the FC region was briefly discussed.

Resonance Raman intensity analysis of the excited-state proton-transfer dynamics of 2-hydroxybenzaldehyde in the charge-transfer/proton-transfer absorption band.

Resonance Raman spectra were obtained for 2-hydroxybenzaldehyde (OHBA) in cyclohexane solution with excitation wavelengths in resonance with the first charge-transfer/proton-transfer (CT/PT) band absorption. These spectra indicate that the Franck-Condon region photodissociation dynamics have multidimensional character with motion predominantly along the nominal C=CH in-plane bend+ring deformation modes (nu9, nu10, nu14, nu16, nu18, nu19, nu20, nu26, nu30, nu31, and nu35) accompanied by a smaller amount of motion along the nominal C=O stretch mode (nu7), the nominal C=C-C(=O) in-plane bend modes (nu33 and nu37), and the nominal ring C-O-H in-plane bend modes (nu9 and nu14). A preliminary resonance Raman intensity analysis was done, and these results for the OHBA molecule were compared to results previously reported for the 2-hydroxyacetophenone (OHAP) molecule. Several proton-transfer tautomers in the ground and excited states were predicted from the results of B3LYP/cc-PVTZ, UB3LYP/cc-PVTZ, and CASSCF/cc-PVDZ level of theory computations. The differences and similarities between the CT/PT band resonance Raman spectra and the vibrational reorganizational energies for the OHBA molecule relative to those for the OHAP molecule are briefly discussed.

Resonance Raman and density functional theory investigation of the photodissociation dynamics of the A-band absorption of (E)-beta-nitrostyrene in cyclohexane solution.

Resonance Raman spectra were obtained for (E)-beta-nitrostyrene in cyclohexane solution with excitation wavelengths in resonance with the charge transfer (CT)-band absorption spectrum. These spectra indicate that the Franck-Condon region photodissociation dynamics have multidimensional character with motion predominantly along the nominal NO(2) symmetric stretch mode (nu(14)), the nominal C=C stretch mode (nu(8)), the nominal benzene ring stretch mode (nu(9)), accompanied by a smaller amount of motion along the nominal ONO symmetric bend/benzene ring stretch mode (nu(34)), the nominal CCH in-plane bending mode (nu(20)), the nominal HC=CH in-plane bending mode (nu(18)), the nominal NO(2) asymmetric stretch mode (nu(11)), the nominal C-N stretch/benzene ring breathing mode (nu(27)), and the nominal CCC trigonal bending mode (nu(25)). A preliminary resonance Raman intensity analysis was done and these results for (E)-beta-nitrostyrene were compared to results previously reported for several nitrobenzene and trans-stilbene compounds. The differences and similarities between the CT-band resonance Raman spectra and vibrational reorganizational energies for (E)-beta-nitrostyrene relative to those for nitrobenzene and trans-stilbene were briefly discussed.

Resonance Raman intensity analysis of the excited state proton transfer dynamics of 2-nitrophenol in the charge-transfer band absorption.

Resonance Raman spectra were obtained for 2-nitrophenol in cyclohexane solution with excitation wavelengths in resonance with the charge-transfer (CT) proton transfer band absorption. These spectra indicate that the Franck-Condon region photodissociation dynamics have multidimensional character with motion along more than 15 normal modes: the nominal CCH bend+CC stretch nu(12) (1326 cm(-1)), the nominal CCC bend nu(23) (564 cm(-1)), the nominal CO stretch+NO stretch+CC stretch nu(14) (1250 cm(-1)), the nominal CCH bend+CC stretch+COH bend nu(15) (1190 cm(-1)); the nominal CCH bend+CC stretch nu(17) (1134 cm(-1)), the nominal CCC bend+CC stretch nu(22) (669 cm(-1)), the nominal CCN bend nu(27) (290 cm(-1)), the nominal NO(2) bend+CC stretch nu(21) (820 cm(-1)), the nominal CCO bend+CNO bend nu(25) (428 cm(-1)), the nominal CC stretch nu(7) (1590 cm(-1)), the nominal NO stretch nu(8) (1538 cm(-1)), the nominal CCC bend+NO(2) bend nu(20) (870 cm(-1)), the nominal CC stretch nu(6) (1617 cm(-1)), the nominal COH bend+CC stretch nu(11) (1382 cm(-1)), nominal CCH bend+CC stretch nu(9) (1472 cm(-1)). A preliminary resonance Raman intensity analysis was done and the results for 2-nitrophenol were compared to previously reported results for nitrobenzene, p-nitroaniline, and 2-hydroxyacetophenone. The authors briefly discuss the differences and similarities in the CT-band absorption excitation of 2-nitrophenol relative to those of nitrobenzene, p-nitroaniline, and 2-hydroxyacetophenone.