Solvatochromic behavior of donor-acceptor-polyenes: dimethylamino-cyano-diphenylbutadiene.

4-(Dimethylamino)-4'-cyano-1,4-diphenylbutadiene (DCB) and 4-(dimethylamino)-2,6-dimethyl-4'-cyano-1,4-diphenylbutadiene (DMDCB) have been characterized spectroscopically. Quantum chemical calculations were performed for comparison. Solvatochromic shifts of the fluorescence were strong and showed a linear dependence on the solvent polarity parameters, whereas shifts in the absorption spectra are very weak only correlate better with the polarizability of the solvents.

Structural modelling of optical and electrochemical properties of 4-aminodiphenylamines - optoelectronic studies on a polyaniline repeating unit.

Amino-diphenylanilines and their planarized and twisted model compounds have been investigated by steady state and time-resolved absorption and emission, as well as by spectroelectrochemistry. These polyaniline model compounds show that the observation of excited states with full charge separation is linked to molecular twisting where the diaminobenzene is the donor and the phenyl group the acceptor. The observable charge transfer fluorescence shows the characteristic features of twisted intramolecular charge transfer (TICT) excited states, i.

Photochemical electrocyclization of the indolinylphenylethenes involving a C-N bond formation.

[reaction: see text] A novel oxidative photodehydrocyclization of indolinylphenylethenes to a polycyclic heteroaromatic cation with good yields was described. Starting from the trans derivative, the phototransformation is a multistep process. The process includes two photochemical reactions and a trans-cis isomerization reaction, followed by an 1-aza-1,3,5-hexatrienic electrocyclic reaction involving the formation of a C-N bond.

Tripodal ligand incorporating dual fluorescent ionophore: a coordinative control of photoinduced electron transfer.

p-(N,N-Dimethylamino)benzenesulfonamide (DMABSA), a dual fluorescent fluorophore, has been derivatized into two new fluoroionophores for transition metal cations. The electron-acceptor sulfonamide group has been N-substituted by a 2-pyridylmethylene group to lead to a bidentate ligand which forms a 2:1 complex with Cu(II). The crystal structure of the copper(II) complex is reported.

Dual fluorescent polyaniline model compounds: steric and temperature effects on excited state charge separation.

Low temperature dual fluorescence of several derivatives of 4-aminodiphenylamine is investigated quantitatively. A strong thermochromic and solvatochromic redshift is indicative of the high dipole moment of the CT state emitting at long wavelength. The combination of steady state and time-resolved data allowed the calculation of the excited-state equilibrium.

Metal-organic compounds: a new approach for drug discovery. N1-(4-methyl-2-pyridyl)-2,3,6-trimethoxybenzamide copper(II) complex as an inhibitor of human immunodeficiency virus 1 protease.

The use of metal-organic complexes is a potentially fruitful approach for the development of novel enzyme inhibitors. They hold the attractive promise of forming stronger attachments with the target by combining the co-ordination ability of metals with the unique stereoelectronic properties of the ligand. We demonstrated that this approach can be successfully used to inhibit the protease of the human immunodeficiency virus (type 1).

Photoswitching of cation complexation with A monoaza-crown dithienylethene photochrome.

A photochromic dithienylethene, bearing a phenyl azacrown as an ionophore and a formyl group as an electron-accepting substituent, changes its binding ability for Ca2+ by a factor higher than 103 by photoirradiation. This new photoionochromic displays a wavelength-dependent competition between fluorescence and photocyclization assigned to a red-shifted absorption of the fluorescing conformer compared to the absorption of the photoreactive conformer.