Bing Xu

Spectroscopic study on the photophysical properties of lanthanide complexes with long chain mono-docosyl phthalate.

Ortho phthalic anhydride was modified with long chain alcohol (1-docosanol) to its corresponding monodocosyl phthalate (22-Phth). Subsequently, three novel lanthanide (Eu3+, Tb3+, and Dy3+) complexes with the long chain monodocosyl phthalate were synthesized and characterized by elemental analysis and Infrared spectra. The photophysical properties of these complexes were studied in detail with ultraviolet-visible absorption spectra, low temperature phosphorescence spectra and fluorescent spectra. The triplet state energy of 22-Phth was determined to be around 25,000 cm−1 from the maximum phosphorescent peak at 400 nm, suggesting 22-Phth is suitable for the sensitization of the luminescence of Eu3+, Tb3+, and Dy3+. The fluorescence excitation and emission spectra for these lanthanide complexes of the three ligands take agreement with the above predict from energy match principle.

Photoluminescence of Novel Zinc Complexes with Long‐Chain Mono (Hexadecyl, Octadecyl, Eicosyl, and Docosyl) Phthalate

Abstract Ortho phthalic anhydride was modified with long‐chain alcohols (1‐hexadecanol, 1‐octadecanol, 1‐eicosanol, and 1‐docosanol) to the corresponding long‐chain phthalate monoester, that is, monohexadecyl phthalate (16‐Phth), monooctadecyl phthalate (18‐Phth), monoeicosyl phthalate (20‐Phth), and monodocosyl phthalate (22‐Phth), respectively. The zinc complexes with these four long‐chain phthalate monoester ligands were synthesized and characterized by elemental analysis, IR and 1H‐NMR spectroscopy. The photophysical properties of these complexes were studied in detail with ultraviolet–visible absorption spectra and fluorescent spectra. Fluorescence studies showed that these zinc complexes exhibit intense violet photoluminescence in the solid state and may be potential candidates for photoactive materials or devices.

Cyclic M(SO2) (M=Zn, Cd) and its Anions: Matrix Infrared Spectra and DFT Calculations

Reaction of laser ablated zinc and cadmium atoms with SO2 molecules was studied by low temperature matrix isolation infrared spectroscopy. Cyclic M(SO2) and anion M(SO2)− (M=Zn, Cd) were produced in excess argon and neon, which were identified by 34SO2 and S18O2 isotopic substitutions. The observed infrared spectra and molecular structures were confirmed by density functional theoretical calculations. Natural charge distributions indicated significant electron transfer from s orbitals of zinc or cadmium metal atom to SO2 ligand and cyclic M(SO2) complexes favored “ion pair” M+(SO2)− formation, which were trapped in low temperature matrices. In addition Zn‐O or Cd‐O bond in M(SO2) exhibited strong polarized covalent character. Reaction of Hg atom with SO2 was also investigated, but no reaction product was observed, due to the relativistic effect that resulted in the contraction of 6s valence shell and high ionization potential of Hg atom.

Spectroscopic observation of photo-induced metastable linkage isomers of coinage metal (Cu, Ag, Au) sulfur dioxide complexes

Coinage metal atom (Cu, Ag, Au) reactions with SO2 were investigated by matrix isolation infrared absorption spectroscopy and density functional theory electronic structure calculations. Both mononuclear complexes M(η(1)-SO2) (M = Ag, Au) and M(η(2)-O2S) (M = Ag, Cu) were observed during condensation in solid argon or neon. Interestingly, the silver containing mononuclear complexes are interconvertible; that is, visible light induces the isomerization of Ag(η(1)-SO2) to Ag(η(2)-O2S) and vice versa on annealing. However, there is no evidence of similar interconvertibility for the Cu(η(2)-O2S) and Au(η(1)-SO2) molecules. These different behaviors are discussed within the bonding considerations for all of the obtained products.

Fabrication and Spectroscopic Characterization of Langmuir-Blodgett Films with Luminescent Rare Earth Complexes of Long Chain Double Functional Ligands Mono-L Phthalate (L = Hexadecyl, Octadecyl and Eicosyl)

In this paper, some novel long chain amphiphillic monoester molecules were designed to afford double functions: film-formation ability and luminescent sensitization ability. Subsequently organized molecular films of rare earth complexes with these functional ligands formulated as ML2NO3 were fabricated by the Langmuir-Blodgett film (LB) technology, where RE denotes rare earth ions Eu3+, Tb3+ and Dy3+; L denotes the long chain carboxylic ligands monohexadecyl phthalate (16-Phth), monooctadecyl phthalate (18-Phth) and monoeicosyl phthalate (20-Phth). The average molecular area was obtained according to the π-A isotherms. The layer structure of the LB films was demonstrated by low-angle X-ray diffraction and the average layer spacing was determined from the Bragg equation. UV absorption intensity increases linearly with the number of LB films layers, which indicates that the LB films are homogeneously deposited. The fluorescence spectra of these LB films were quite different from those of their solid complexes. It reveals that the long chain ester ligands are suitable for the excited states of Tb3+ and Dy3+ in the LB films as well as in the solid complexes, but not match with the europium ion in the LB films.

Matrix Infrared Spectra and Theoretical Calculations of Fluoroboryl Complexes F2B–MF (M = C, Si, Ge, Sn and Pb)

The reactions of laser-ablated C, Si, Ge, Sn, and Pb atoms with BF3 have been studied using matrix isolation Fourier transform infrared (FTIR) spectroscopy and density functional theoretical (DFT) calculations. All atoms generate the inserted complex F2B-MF, which were trapped in inert gas and identified by the isotopic substitutions and DFT frequency calculations. DFT and CCSD(T) calculations show that triplet F2B-CF is the most stable isomer with two singly occupied molecular orbitals, while singlet F2B-MF (M= Si, Ge, Sn and Pb) molecules possess a near right angle B-M-F moiety with lone pair electrons on the M atom. The bonding difference between C and other group 14 atoms is mainly caused by relativistic effect, which is that, for heavier metal atom valences, s and p orbitals have a lower tendency to form hybrid orbitals.

Matrix-Infrared Spectra and Structures of HM–SiH3 (M = Ge, Sn, Pb, Sb, Bi, Te Atoms)

The reactions of Ge, Sn, Pb, Sb, Bi, and Te atoms with silane molecules were studied using matrix-isolation Fourier transform infrared spectroscopy and density functional theoretical (DFT) calculations. All metals generate the inserted complexes HM-SiH3, which were stabilized in an argon matrix, while H2M═SiH2 and H3M≡SiH were not observed. DFT and CCSD(T) calculations show the insertion complex HM-SiH3 is the most stable isomer with a near right angle H-M-Si moiety. However, silydene complexes H2M═SiH2 (M = C, Si) were calculated and identified as the most stable complexes with the lighter elements. The bonding difference is mainly due to relativistic effects, which is that for heavier metal atoms valence s and p orbitals have a lower tendency to form hybrid orbitals.

Double and Triple Si–H–M Bridge Bonds: Matrix Infrared Spectra and Theoretical Calculations for Reaction Products of Silane with Ti, Zr, and Hf Atoms

Infrared spectra of matrix isolated dibridged Si(μ-H)2MH2 and tribridged Si(μ-H)3MH molecules (M = Zr and Hf) were observed following the laser-ablated metal atom reactions with SiH4 during condensation in excess argon and neon, but only the latter species was observed with titanium. Assignments of the major vibrational modes, which included terminal MH, MH2 and hydrogen bridge Si-H-M stretching modes, were confirmed by the appropriate SiD4 isotopic shifts and density functional vibrational frequency calculations (B3LYP and BPW91). The Si-H-M hydrogen bridge bond is calculated as weak covalent interaction and compared with the C-H···M agostic interaction in terms of electron localization function (ELF) analysis and noncovalent interaction index (NCI) calculations. Furthermore, the different products of Ti, Zr, and Hf reactions with SiH4 are discussed in detail.