Hamid Dhimane

Substitution Effect on the One- and Two-photon Sensitivity of DMAQ “Caging” Groups

The systematic SAR study of a caging group showed a strong influence of the position of the donor dimethylamino group on the efficiency of photolysis of the DMAQ (2-hydroxymethylene-(N,N-dimethylamino)quinoline) caged acetate under one-photon near-UV or two-photon near-IR excitation. Photorelease of l-glutamate by the most efficient 8-DMAQ derivative strongly and efficiently activated glutamate receptors, generating large, fast rising responses similar to those elicited by glutamate photoreleased from the widely used MNI-caged glutamate.

Two-Photon “Caging” Groups: Effect of Position Isomery on the Photorelease Properties of Aminoquinoline-Derived Photolabile Protecting Groups

High two-photon photolysis cross sections and water solubility of probes are important to avoid toxicity in biomedical applications of photolysis. Systematic variation of the position of a carboxyl electron-withdrawing group (EWG) on photolysis of 8-dimethylaminoquinoline protecting groups identified the C5-substituted isomer as a privileged dipole. The 5-benzoyl-8-DMAQ substitution yields a caging group with an enhanced two-photon uncaging cross section (δu = 2.0 GM) and good water solubility (c ≤ 50 mM, pH 7.4).

Quinoline‐Derived Two‐Photon Sensitive Quadrupolar Probes

Quadrupolar probes derived from 8-dimethylamino-quinoline (8-DMAQ) having a pegylated fluorene core were prepared and studied under one-photon (λ=365u2005nm) and two-photon (TP) (λ=730u2005nm) irradiation conditions. Compound 1u2009a was identified as the most efficient probe by UV activation that showed sequential release of acetic acid as a model. Although the probe showed high two-photon absorption it stayed inert under femtosecond irradiation conditions. Fast and selective photolysis was observed, however, by using picosecond irradiation conditions with a remarkably high TP uncaging cross-section (δu =2.3u2005GM).

5-Aryl-dimethylamino quinoline-derived two-photon sensitive probes

2-Hydroxymethylene-8-dimethylamino quinoline-(DMAQ) derived photosensitive probes were prepared and tested under 366 nm and 730 nm 150 fs pulsed (“two-photon”) irradiation conditions. Brief bursts of photolysis of 250 μM solution of the kainate derivative of 2f generated sufficient kainate in a small spot to excite large inward currents and somatic spiking in Purkinje neurons.

Synthesis of Three Regioisomeric (7-Methoxychromenonyl)methyl Guanosine 5'-Phosphates

Abstract Herein we describe the synthesis of three new (7-methoxychromenonyl)methyl 2-N-propionyl-2′,3′-isopropylideneguanosine 5′-phosphate diesters, potentially photolabile nucleotides, via an H-phosphonate strategy. The stability of these compounds toward acidic and basic conditions was evaluated during the nucleoside moiety deprotection.

Photoinduced Electron Transfer (PET)-Mediated Fragmentation of Picolinium-Derived Redox Probes

The photolysis of covalently linked N-alkyl picolinium phenylacetate-carbazole dyads was analyzed experimentally and by using density functional theory (DFT) and time dependent-DFT (TD-DFT) calculations. In contrast to earlier observations efficient one and two-photon fragmentations conditions were found for 15u2009c (δu =0.16u2005GM at 730u2005nm) opening the way for the design of a novel class of caged compounds.

Quinoline-Derived Two-Photon-Sensitive Octupolar Probes

Abstract A systematic study on quinoline‐derived light sensitive probes, having third‐order rotational symmetry is presented. The electronically linked octupolar structures show considerably improved linear and nonlinear photophysical properties under one‐ and two‐photon irradiation conditions compared to the corresponding monomers. Photolysis of the three acetate derivatives shows strong structure dependency: whereas irradiation of the 6‐ and 7‐aminoquinoline derivatives resulted in fast intramolecular cyclization and only trace amounts of fragmentation products, the 8‐aminoquinoline derivative afforded clean and selective photolysis, with a sequential release of their acetate groups (δ u [730]=0.67u2005GM).