Resonance Raman spectra and cross sections of a "push-pull" chromophore containing a julolidine donor and a thiobarbituric acid acceptor have been measured in dilute solution in five solvents having a wide range of polarities (cyclohexane, 1,4-dioxane, dichloromethane, acetonitrile, and methanol) at excitation wavelengths spanning the strong visible charge-transfer absorption band. The absolute Raman excitation profiles and absorption spectra are simulated using time-dependent wave packet propagation techniques to determine the excited-state geometry changes along the ∼30 Raman-active vibrations as well as the solvent reorganization energies. Several vibrational modes undergo significant (5-15 cm -1 ) frequency changes as the solvent is varied, signaling solvent polarity effects on the ground-state electronic structure. The excited-state geometry changes are solvent dependent for some vibrational modes but not for others. The total vibrational reorganization energy decreases, and the solvent reorganization energy increases with increasing solvent polarity in all solvents except the one protic solvent, methanol, which is anomalous in both respects. Tentative assignments are made for the ground-state vibrational modes by comparison of the Raman frequencies and infrared frequencies and intensities with those calculated using density functional theory, as well as by comparison with model compounds. The results are discussed within the context of the two-state valence-bond model for the electronic properties of conjugated push-pull chromophores.

The essential oil composition of two different styrax gums, Asian and American were analysed by GC and GC-MS. Fifty-eight components representing more than 99.4% of the oil from Asian styrax gum and 57 components representing more than 99% of the oil from American styrax gum were identified. The major components were styrene (70.4 and 30.9% respectively), α-pinene (19.4 and 19.6%) and β β β β β-caryophyllene (0.2 and 20.2%) for the two oils. These results show that we could identify an Asian from an American styrax by relative amounts of styrene and β β β β β-caryophyllene in the essential oils.

Sclareol is a high-value natural product obtained by solid/liquid extraction of clary sage (Salvia sclarea L.) inflorescences. Because processes of excretion and accumulation of this labdane diterpene are unknown, the aim of this work was to gain knowledge on its sites of accumulation in planta. Samples were collected in natura or during different steps of the industrial process of extraction (steam distillation and solid/liquid extraction). Samples were then analysed with a combination of complementary analytical techniques (gas chromatography coupled to a mass spectrometer, polarized light microscopy, environmental scanning electron microscopy, two-photon fluorescence microscopy, second harmonic generation microscopy). According to the literature, it is hypothesized that sclareol is localized in oil pockets of secretory trichomes. This study demonstrates that this is not the case and that sclareol accumulates in a crystalline epicuticular form, mostly on calyces.

Static-headspace (S-HS), headspace-solid phase microextraction (HS-SPME) and headspace sorptive extraction (HSSE) have been applied to the analysis of different grades of benzoin gums Siam and Sumatra. This study led to the identification of 58 compounds by GC-RI and GC-MS: 42 of them were characterized in Siam benzoin gum (grades 3 and 5) and 40 of them in Sumatra (grades B and D). SPME using divinylbenzene/carboxen/polydimethylsiloxane fiber and HSSE are complementary in these conditions and seem to be the most suitable techniques to identify volatile compounds of benzoin gums. S-HS is less sensitive but represents a good method for the quality control of these gums. For this reason it has been applied directly coupled to mass spectrometry for a rapid differentiation between several benzoin gum qualities.

The volatile extract composition of two different benzoin gums, Siam and Sumatra, were analysed by GC-MS. Twenty components representing more than 99.1% of the oil from Siam and 29 components representing more than 97.4% of the oil from Sumatra were analysed. The major components were benzyl benzoate (76.1-80.1%) for the two oils and benzoic acid (12.5%), methyl benzoate (1.5%) and allyl benzoate (1.5%) for Siam, and styrene (2.3%), cinnamic acid (3.5%) and benzyl cinnamate (3.3%) for Sumatra. Volatile compounds of oils and crushed benzoins were also studied using solid-phase microextraction (SPME) employing carboxen/polydimethylsiloxane and carbowax/divinylbenzene fibres.