Carstensenstryhn4467

A series of D-π-A chromophores based on allylidenemalononitrile electron-withdrawing group was designed. The influence of the amino-electron-donating group on the photophysical properties was studied. These compounds, highly thermally stable, exhibit orange-red emission in solution and in solid state. The experimental results have been rationalized by theoretical DFT calculations. The second order nonlinear optical properties were also studied using the electric field induced second harmonic generation (EFISH) method.This work demonstrated the effect of charge transfer (CT) induced by metal surface plasmon resonance (SPR) on surface-enhanced Raman scattering (SERS). We designed an Ag-ZnSe nanostructure and introduced p-aminothiophenol (PATP) molecules to form an Ag-ZnSe-PATP system. The proposed method compensates for the CT difficulty in wide-band-gap semiconductors, which was initiated by the SPR of Ag. The Raman intensity is enhanced differently depending on the action of excitation light of different wavelengths. The concept of the CT degree was introduced to analyze this intriguing phenomenon. The system constructed in this work combines the electromagnetic enhancement mechanism and the chemical enhancement mechanism, which helps further understand the SERS mechanism and provides important references for SERS research on wide-band-gap semiconductors.This work presents new experimental and theoretical insights on vibrational spectra of CH3I and CD3I in the liquid phase. For the first time, we provided the contributions from different vibrational modes to mid-infrared (MIR) and near-infrared (NIR) spectra and estimated the extent of anharmonicity in the MIR region. Direct comparison of the intensities from ATR-IR and NIR transmission spectra was possible due to normalization of ATR-IR spectra. As a reference for normalization, we applied the area of the νs(CH3)/νs(CD3) band recorded in transmission mode. Our results show that the corresponding vibrational modes of CH3I and CD3I have similar contributions to the total intensity (MIR + NIR), however, these contributions are distributed in a different way between MIR and NIR regions. As expected, most of intensity in MIR spectra originates from the fundamental transitions (>90%). The fundamental bands together with the first overtones and the binary combinations contribute to more than 99% of MIR intensity for both compounds. Therefore, reliable reconstruction of MIR spectra can be achieved by considering only these vibrational modes. On the other hand, accurate simulation of NIR spectra requires including the higher-order transitions. In the case of CD3I, the fourth-order transitions contribute to 12.7% of NIR intensity. The contributions from NIR region are significantly smaller than those from MIR range and were estimated to be 6.7% for CH3I and 2.3% for CD3I. The theoretical calculations provide a reasonable estimation of the total contribution from the fundamental bands. click here Yet, the calculated contributions from the anharmonic transitions are different from those obtained from the experimental data. MIR spectra of CH3I and CD3I reveal an unexpected increase in the intensity of some overtones and combination bands indicating the presence of Fermi resonances. These resonances are responsible for differences in contributions from the first overtones and binary combinations between CH3I and CD3I.Exploring a new multi-responsive pyranone chemosensor capable of sensing copper ions specifically and selectively through colorimetric, UV-Vis absorption and fluorescence methods is of great importance. In this piece of work, a novel pyranone based Schiff base ligand 4-Hydroxy-6-methyl-3-[1-(2-morpholin-4-yl-ethylimino)-ethyl]-pyran-2-one (DM) was synthesized by the condensation of dehydroacetic acid and 4-(2-aminoethyl) morpholine. The structural determination of ligand DM was executed using distinct spectral techniques i.e.,1H NMR, 13C NMR, FT-IR and HR-MS techniques. The reported Schiff base DM showed an immediate colorimetric change from pale yellow to colorless accompanied by a strong change in the UV-Vis absorption band onto the addition of Cu (II) ions. This metal ligand chelation leads a decrease in ICT process. Also the decrease in fluorescence emission intensity of Schiff base DM with Cu (II) ions addition showed its turn-off behavior towards copper ions. Further absorption/ emission titration studies, Job's plot, HR-MS and 1H NMR titration data designated 21 stoichiometric ratio between DM and Cu (II) ions respectively. Density functional theory studies were also performed to authenticate the binding mechanism theoretically. The sensitivity of Schiff base DM towards Cu (II) ions was applicable at every pH conditions and at the same time DM exhibited selectivity towards Cu (II) ions with a negligible interference of other metal ions. DM showed a detection limit of 7.7 nM towards copper ions via fluorescence emission studies. The best part about DM is that it has good stability but showed an instant chemical reversibility when titrated with EDTA solution.White light emission phosphors are widely researched for application in lighting and display fields. However, the poor thermal stability is a real problem for the known single-phased white phosphors, which limits their further application. In this paper, Ca19Na2Mg(PO4)14 xDy3+, yTm3+ (CNMP, 0 ≤ x ≤ 0.06, y = 0, 0.01) phosphors with adjustable emission and good thermal stability are synthesized. The X-ray diffraction and X-ray energy dispersive spectrometer measurement distinctly confirm the successful synthesis of CNMP xDy3+, yTm3+ (CNMP, 0 ≤ x ≤ 0.06, y = 0, 0.01). The photoluminescence results reveal that CNMP Dy3+ shows characteristic excitation peaks in the range of 350-450 nm, and mainly exhibits strong yellow emission around 575 nm ascribed to the 4F9/2-6H13/2 transitions of Dy3+. To compensate the deficiency of blue light emission of CNMP Dy3+, the trivalent Tm3+ ion is co-doped owing to its characteristic blue emission at 450 nm due to its 1D2-3F4 transitions. Therefore, the emission of CNMP Dy3+, Tm3+ can be tuned from blue light region with CIE coordinates of (0.1649, 0.0387) to white light region with CIE coordinates of (0.3001, 0.3003) and finally move to yellow light region with CIE coordinates of (0.3732, 0.4493) through adjusting the doping ratio of Dy3+/Tm3+. The energy transfer efficiency and the energy transfer mechanism from Tm3+ to Dy3+ are further investigated. Moreover, CNMP Dy3+, Tm3+ exhibites a high thermal stability and the emission intensity still keeps 84% of the initial intensity of Dy3+ at 230 °C. These outstanding properties show that Ca19Na2Mg(PO4)14 Dy3+, Tm3+ have great advantages and potentiality for applying in solid state lighting.