Resonance raman spectra and excitation profiles of soret-excited metalloporphyrins

Resonance Raman spectra of nickel, chromium, and copper porphyrins, excited at their Soret maxima, show decreasing scattering intensity due to depolarized modes. This order correlates with diminished ¹Q(0-0) absorption in the porphyrins. The data are interpreted in terms of Jahn-Teller distortions in both Q and B states. General agreement between predicted and observed excitation profiles of nickel etioporphyrin I support a vibronic treatment of the excited states. The effect of tight focusing of the incident beam is to quench most Raman scattering intensity, except the 1384 cm^?1 line of the nickel complex.     

Photoluminescent metal-sulfur clusters derived from tetrathiometalates: metal-to-metal charge-transfer excited states of d0-d10 heterobimetallic sulfido clusters with bulky phosphine ligands

Reactions of MS4(2-) (M = Mo, W) with M'(PCy3)X (M'=Ag/Au, X= ClO4/Cl) and [Cu2(dcpm)2(MeCN)2](ClO4)2 (dcpm = bis(dicyclohexylphosphino)methane) afforded heterometallic sulfido clusters [M'2(PCy3)2(MS4)] (M=Mo, M'=Au: 2; M=W, M'=Ag: 3, Au: 4) and [Cu4(dcpm)4(MS4)](ClO4)2 (M=Mo: 5 x (ClO4)2, W: 6 x (ClO4)2), all of which, except 4, have been characterized by X-ray structure determination. Clusters 5 x(ClO4)2 and 6 x (ClO4)2 feature unusual 16-membered [Cu4P5C4] metallamacrocycles formed on the respective tetrathiometalate anion templates and have unusually long Cu-S bonds and Cu...M distances for metal sulfur clusters that contain a saddle-shaped [Cu4MS4] core. Low-energy absorption bands are observed in their electronic spectra at approximately 562 and 467 nm, respectively, assignable to MMCT transitions; quasireversible reduction waves are observed with E(1/2) = -1.43 (52+) and -1.78 V (62+) versus FeCp2(0/+); and they are emissive either in the solid state or in solution. The emission of 6(2+) can be quenched by both electron acceptors, such as methylviologen, or electron donors, such as aromatic amines, with the excited state reduction potential E(62+*/6+) estimated to be approximately 1.13V versus a normal hydrogen electrode.     

Synthesis, characterization, electrochemistry and luminescence studies of heterometallic gold(I)-rhenium(I) alkynyl complexes

The present work provides a brief summary review of the chemistry of luminescent gold(I) alkynyls and their ability to form heterometallic complexes. A series of luminescent heterometallic gold(I)-rhenium(I) alkynyl complexes has been synthesized and characterized. Their electrochemical and photophysical properties have been studied and their emission origins elucidated.     

Organic triplet emissions of arylacetylide moieties harnessed through coordination to [Au(PCy(3))]+. Effect of molecular structure upon photoluminescent properties

A family of mono- and binuclear Cy(3)P-supported gold(I) complexes containing various pi-conjugated linear arylacetylide ligands, including the two homologous series (Cy(3)P)Au(Ctbd1;CC(6)H(4))(n)()(-)(1)(Ctbd1;CPh) and (Cy(3)P)Au(Ctbd1;CC(6)H(4))(n)()Ctbd1;CAu(PCy(3)) (n = 1-4), have been prepared. X-ray crystal analyses revealed no intermolecular aurophilic interactions in their crystal lattice. The lowest-energy singlet transitions are predominately intraligand in nature and exhibit both phenyl and acetylenic (1)(pipi) character. Strong photoluminescence is detected in solid and solution states under ambient conditions, with lifetimes in the microsecond regime. For complexes with a single arylacetylide group, only phosphorescence from the arylacetylide (3)(pipi) state is observed. Vibrational spacings in the solid-state emission spectra can be attributed to a combination of phenyl ring deformation and symmetric phenyl ring and Ctbd1;C stretches. Additional delayed-fluorescence emission is recorded for complexes with multiple p-arylacetylide units, and this is attributed to a triplet-triplet annihilation process. The phosphorescence energy of these complexes are readily modified by altering the length of the conjugated arylacetylide system, while the intensity of phosphorescence relative to fluorescence decreases when the p-arylacetylide chain is elongated. Information regarding the nature and relative energies of arylacetylide singlet and triplet excited states has been derived from the two homologous series and extrapolated to polymeric arylacetylide species. The (3)(pipi) excited-state reduction potentials E degrees [Au(+)/Au] (Au = 1a, 2, and 4) are estimated to be -1.80, -1.28, and -1.17 V versus SSCE, respectively.     

Nuclear magnetic resonance spectra of polyfluorobuta-1,3-dienes. Part II [1]. Variable temperature study of two 2-azabutadienes

The two perfluoro-azadienes CF₂N.CRCF₂ (R = CF₃ or CF₂Cl) show temperature dependent ¹⁹F n.m.r. spectra, with non-equivalent fluorine nuclei of the CF₂N portion at low temperatures, which coalesce due to inversion at the nitrogen at higher temperatures (ΔG3 = 60 kJ mol^?1). N.m.r. parameters have been obtained. One of the five-bond FF coupling constants is much larger ($\text{ca}$. 24 Hz) than the remainder (0·5–5·5 Hz), possibly due to ‘through-space’ coupling of fluorines in the $\text{cis}$-skew conformation.     

High-performance liquid chromatographic analysis for a non-chromophore-containing phosphatidyl inositol analog, 1-((1-O-octadecyl-2-O-methyl-sn-glycero)phospho)-1D-3-deoxy-myo-inositol, using indirect UV detection

Phosphatidylinositide-3-kinase (PI3 kinase) is an important constituent of growth factor regulation. It is also involved in oncogene signaling pathways. An ether-containing phosphatidyl inositol(PI) analog, OMDPI, 1-[(1-O-octadecyl-2-O-methyl-sn-glycero)-phospho]-1D-3-deoxy-myo-inositol, is a potent inhibitor of this pathway and may be clinically useful in the treatment of a variety of neoplasms. OMDPI is currently being investigated as an anti-tumor agent by the National Cancer Institute, NIH. OMDPI, a non-chromophore-containing PI analog, is not directly adaptable to the commonly used UV detection of HPLC. This paper reports the development and validation of an HPLC assay for OMDPI based on indirect UV detection, in which a UV-absorbing ion-pair reagent (the probe), protriptyline, is added to the mobile phase to induce a signal for the compound. The method is sensitive (limit of detection <5 microl of 1 microg/ml or 5 ng), precise (R.S.D.<2.5%), linear (r2=0.9995) and accurate (error<0.7%). It is superior to refractive index detection and evaporative light scattering detection in either sensitivity or linearity and does not require special equipment.