13940-36-8Relevant articles and documents
Photoinduced energy transfer between water-soluble CdTe quantum dots and aluminium tetrasulfonated phthalocyanine
Idowu, Mopelola,Chen, Ji -Yao,Nyokong, Tebello
, p. 290 - 296 (2008)
Thiol stabilized CdTe quantum dots (QDs) synthesized in aqueous phase were used as energy donors to aluminium tetrasulfonated phthalocyanine (AlTSPc) through fluorescence resonance energy transfer (FRET). Energy transfer occurred from the QDs to AlTSPc upon photoexcitation of the QDs. An enhancement in efficiency of energy transfer with the nature of the carboxylic thiol stabilizers on the QDs was observed. The results showed that for enhanced FRET to occur, the donor-acceptor distance has to be lower than the critical distance. The quenching constant K as well as the binding constant kb values were calculated suggesting strong interaction of the QDs with the AlTSPc. Study of the photophysics of AlTSPc in the presence of the QDs revealed a high triplet state yield, hence the possibility of using QDs in combination with phthalocyanines as photosensitizers in photodynamic therapy. The triplet state lifetimes of AlTSPc in the presence of the QDs were calculated and the lifetime in the presence of CdTe capped with 3-mercaptopropionic acid (MPA) was found to be the longest. MPA capped QD in a mixture with AlTSPc resulted in long triplet lifetime and high triplet yield of the latter, and high energy transfer efficiency, hence was found to be most suitable as a potential candidate for photodynamic therapy of cancer studies. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Heavy hydrides: H2Te ultraviolet photochemistry
Underwood,Chastaing,Lee,Wittig
, (2008/10/09)
The room-temperature ultraviolet absorption spectrum of H2 Te has been recorded. Unlike other group-6 hydrides, it displays a long-wavelength tail that extends to 400 nm. Dissociation dynamics have been examined at photolysis wavelengths of 266 nm (which lies in the main absorption feature) and 355 nm (which lies in the long-wavelength tail) by using high- n Rydberg time-of-flight spectroscopy to obtain center-of-mass translational energy distributions for the channels that yield H atoms. Photodissociation at 355 nm yields TeH (Π 12 2) selectively relative to the TeH (Π 32 2) ground state. This is attributed to the role of the 3 A′ state, which has a shallow well at large RH-TeH and correlates to H+TeH (Π 12 2). Note that the Π 12 2 state is analogous to the P 12 2 spin-orbit excited state of atomic iodine, which is isoelectronic with TeH. The 3 A′ state is crossed at large R only by 2 A″, with which it does not interact. The character of 3 A′ at large R is influenced by a strong spin-orbit interaction in the TeH product. Namely, Π 12 2 has a higher degree of spherical symmetry than does Π 32 2 (recall that I (P 12 2) is spherically symmetric), and consequently Π 12 2 is not inclined to form either strongly bonding or antibonding orbitals with the H atom. The 3 A′ ←X transition dipole moment dominates in the long-wavelength region and increases with R. Structure observed in the absorption spectrum in the 380-400 nm region is attributed to vibrations on 3 A′. The main absorption feature that is peaked at ～240 nm might arise from several excited surfaces. On the basis of the high degree of laboratory system spatial anisotropy of the fragments from 266 nm photolysis, as well as high-level theoretical studies, the main contribution is believed to be due to the 4 A″ surface. The 4 A″ ←X transition dipole moment dominates in the Franck-Condon region, and its polarization is in accord with the experimental observations. An extensive secondary photolysis (i.e., of nascent TeH) is observed at 266 and 355 nm, and the corresponding spectral features are assigned. Analyses of the c.m. translational energy distributions yield bond dissociation energies D0. For H2 Te and TeH, these are 65.0±0.1 and 63.8±0.4 kcalmol, respectively, in good agreement with predictions that use high-level relativistic theory.
The intriguing near-ultraviolet photochemistry of H2Te
Underwood,Chastaing,Lee,Boothe,Flood,Wittig
, p. 483 - 490 (2008/10/08)
The ultraviolet absorption spectrum of H2Te has a long wavelength tail that extends to 400 nm. Photodissociation at 355 nm yields TeH(2 1/2) selectively relative to the 2 3/2 ground state; the transition moments for these channels lie in, and perpendicular to, the molecular plane, respectively. Vibrational structure in the region 380-400 nm is consistent with a shallow well in the adiabat leading to 2 1/2, akin to the one in HI leading to I(2P1/2). These effects have no counterparts with the light Group 6A dihydrides.
