Yavor Kamdzhilov

University of Basel

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Jakob Wirz

University of Basel

Bruno Hellrung

University of Basel

Marek Mac

Jagiellonian University

Markus A. Schwörer

University of Basel

Elizabeth D. Cope

Georgia Institute of Technology

Martin Gáplovský

Comenius University Bratislava

Dominik Heger

Masaryk University

Michel Calame

University of Basel

Sense Jan van der Molen

Leiden University

Julio F. Mata‐Segreda

Universidad de Costa Rica

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University of Basel

University of Kansas

Jagiellonian University

Universidad de Costa Rica

University of Toronto

Masaryk University

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Swiss Federal Institute of Aquatic Science and Technology

University of Hong Kong

Swiss Federal Laboratories for Materials Science and Technology

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A New Photoremovable Protecting Group - Synthesis and Reaction Mechanism

Yavor Kamdzhilov

A new photoremovable protecting group, allowing for irradiation up to 400 nm, is introduced. A simple synthetic route to three derivatives was described and their photochemistry in aqueous solutions and acetonitrile was investigated. Quantum yields of substrate deprotection Фdep (HBr, CH3COOH and HOPO(OEt)2) were measured spectrophotometrically and by HPLC and were found to be satisfactory (Φ = 0.3 – 0.7). Nucleofugacity of the leaving group, the nature of solvent, and the pH determine the reaction mechanism. A reactive intermediate, expelling the protected substrate, was detected by laser flash photolysis (LFP) and by time-resolved infrared spectroscopy (TRFTIR), and the release rate constants of substrates were found to be in the microsecond time-domain. A mechanistic scheme rationalizing our observation is proposed.

Flash photolysis

Protecting group

Microsecond

10.5451/unibas-004088430

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Citations (1)

The Photo-Favorskii Reaction of p-Hydroxyphenacyl Compounds Is Initiated by Water-Assisted, Adiabatic Extrusion of a Triplet Biradical

Journal of the American Chemical Society (2008)

Richard S. Givens Dominik Heger Bruno Hellrung Yavor Kamdzhilov Marek Mac

The p-hydroxyphenacyl group 1 is an effective photoremovable protecting group, because it undergoes an unusual photo-Favorskii rearrangement concomitant with the fast release (<1 ns) of its substrates in aqueous solution. The reaction mechanism of the diethyl phosphate derivative 1a was studied by picosecond pump−probe spectroscopy, nanosecond laser flash photolysis, and step−scan FTIR techniques. The primary photoproduct is a triplet biradical, 33, with a lifetime of about 0.6 ns. The release of diethyl phosphate determines the lifetime of the triplet state T1(1a), τ(T1) = 60 ps in wholly aqueous solution. Formation of a new photoproduct, p-hydroxybenzyl alcohol (6), was observed at moderate water concentrations in acetonitrile. It is formed by CO elimination from the elusive spirodione intermediate (4), followed by hydration of the resulting p-quinone methide (5). Computational studies show that CO elimination from the spirodione is a very facile process.

Flash photolysis

Derivative (finance)

10.1021/ja7109579

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Citations (72)

Photorelease of Alcohols from 2-Nitrobenzyl Ethers Proceeds via Hemiacetals and May Be Further Retarded by Buffers Intercepting the Primary aci-Nitro Intermediates

Journal of the American Chemical Society (2005)

Bruno Hellrung Yavor Kamdzhilov Markus A. Schwörer Jakob Wirz

The mechanism for the photoinduced release of glycolic acid from its 2-nitrobenzyl ether was reinvestigated. The pH-dependent rate constants of the thermal reactions initiated by irradiation are similar to those reported previously for 2-nitrobenzyl methyl ether. A hemiacetal intermediate that limits the release rate of glycolic acid at pH values ≤7 was identified by time-resolved IR and UV measurements. Furthermore, 2-(2'-nitrosophenyl)-1,3-dioxolan-4-one, a long-lived intermediate formed by intramolecular trapping of the aci-tautomer, was observed and characterized.

Primary (astronomy)

Primary alcohol

10.1021/ja052300s

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Citations (22)

Synthesis and reaction mechanism of a photoremovable protecting group based on 1,4-naphthoquinone

Photochemical & Photobiological Sciences (2007)

Yavor Kamdzhilov Jakob Wirz

Protecting group

Naphthoquinone

Flash photolysis

10.1039/b706318k

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Citations (15)

Photochemical reaction mechanisms of 2-nitrobenzyl compounds: 2-Nitrobenzyl alcohols form 2-nitroso hydrates by dual proton transfer

Photochemical & Photobiological Sciences (2004)

Martin Gáplovský Yuri V. Il’ichev Yavor Kamdzhilov Svetlana V. Kombarova Marek Mac

Nitroso

Flash photolysis

Acetophenone

Benzaldehyde

Nitroso Compounds

Benzyl alcohol

Reaction intermediate

10.1039/b409927c

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Citations (95)

Deprotonation and protonation studies of some substituted 1,4- and 9,10-anthraquinones

Dyes and Pigments (2002)

Tzvetanka Philipova Christina Ivanova Yavor Kamdzhilov Marı́a Teresa Molina

Anthraquinones

10.1016/s0143-7208(02)00016-5

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Citations (16)

Spectroscopy of Molecular Junction Networks Obtained by Place Exchange in 2D Nanoparticle Arrays

The Journal of Physical Chemistry C (2007)

Laetitia Bernard Yavor Kamdzhilov Michel Calame Sense Jan van der Molen Jianhui Liao

Well ordered nanoparticle arrays were prepared on Si/SiO2 surfaces from alkanethiol-coated Au nanoparticles via self-assembly and micro-contact printing. We study the insertion of conjugated molecular species within the nanoparticle arrays via spectroscopic and electrical transport measurements. Upon exchange of the alkanethiol chains with the conjugated oligomers, the conductance of the network increases by one to 3 orders of magnitude. In addition, the absorption spectra in the visible light range show a red-shift of the surface plasmon resonance (SPR). The latter shift, which is due to the difference in permittivity between alkanes and conjugated oligomers, can be understood within Mie and Maxwell−Garnett theory. Finally, infrared absorption spectra provide direct spectroscopic evidence that the conjugated oligomers can be not only inserted but also, subsequently, fully removed from the nanoparticle arrays via place-exchange. The reversibility of the exchange process demonstrates the potential of these structures as a platform for molecular electronics.

10.1021/jp077095c

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Citations (63)

Primary photoreactions of phylloquinone (vitamin K1) and plastoquinone-1 in solution

Photochemical & Photobiological Sciences (2003)

Martin-A. Hangarter Aldo Hörmann Yavor Kamdzhilov Jakob Wirz

Flash photolysis

Plastoquinone

10.1039/b301808n

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Citations (46)