Raúl Pérez-Ruiz
Polytechnic University of Valencia
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Publication
Featured researches published by Raúl Pérez-Ruiz.
Angewandte Chemie | 2012
Dipl.-Chem. Darius Paul Kranz; Axel G. Griesbeck; Ronald Alle; Raúl Pérez-Ruiz; Jörg M. Neudörfl; Klaus Meerholz; Hans-Günther Schmalz
This work was supported by the Universitat zu Koln and the Fonds der Chemischen Industrie. We thank Dr. S. Neufeind and Dipl.-Chem. A. M. Heinsch fur stimulating discussions.
Organic Letters | 2011
Raúl Pérez-Ruiz; Luis R. Domingo; M. Consuelo Jiménez; Miguel A. Miranda
The feasibility of an electron transfer imino-Diels-Alder reaction between N-benzylideneaniline and arylalkenes in the presence of a pyrylium salt as a photosensitizer has been demonstrated by a combination of product studies, laser flash photolysis (LFP), and DFT theoretical calculations. A stepwise mechanism involving two intermediates and two transition states is proposed.
Journal of Physical Chemistry B | 2011
Raúl Pérez-Ruiz; Rafael Alonso; Edurne Nuin; Inmaculada Andreu; Ma Consuelo Jiménez; Miguel A. Miranda
Three drugs containing the naphthalene (NP) chromophore, namely, naproxen (NPX), propranolol (PPN), and cinacalcet (CIN), but with different affinities toward serum albumins (SAs) and α-1-acid glycoproteins (AAGs) have been employed for the assessment of drug distribution in binary SA/AAG systems. These three drugs represent an appropriate choice for checking whether a methodology based on transient absorption spectroscopy of a given reporter can be employed for discrimination between different distribution patterns in multicompartmental biological media. Thus, upon laser flash photolysis (LFP) of NPX, PPN, and CIN in the presence or absence of proteins, the NP triplet excited state ((3)NP*) at ∼420 nm was always detected, although the kinetics of the decay traces was structure- and medium-dependent. In aerated PBS, only a very short triplet lifetime (τ(T)) was found (1-2 μs). By contrast, in the presence of SAs, two longer triplet lifetimes (5-76 μs) were observed, ascribed to (3)NP* within site I and site II. Upon binding to AAGs, only a long τ(T) (15-47 μs) was found. When the two proteins were present simultaneously in the same media, fitting of the decay traces was clearly consistent with a distribution of the drug between the different biological compartments and the bulk solution, which correlates well with the known protein affinities of every drug. Experiments were performed in both human (HSA/HAAG) and bovine protein media (BSA/BAAG). The results showed that SAs are the major carriers for NPX; by contrast, PPN binds preferentially to AAGs. An intermediate situation was found for CIN, which presents comparable affinity for both proteins. The results obtained for the two enantiomers of each drug were very similar, although a small stereodifferentiation was observed between the triplet lifetimes in the protein binding sites.
Journal of Physical Chemistry A | 2009
Luis R. Domingo; Raúl Pérez-Ruiz; Juan E. Argüello; Miguel A. Miranda
The mechanistic aspects of the radical cationic version of the [4 + 2] cycloaddition between thiobenzophenone 1 and three aryl-substituted alkenes 2a-c have been studied using DFT methods at the UB3LYP/6-31G* level of theory. In the ground state, the Diels-Alder reaction follows an asynchronous concerted mechanism; the large activation energy associated with bond formation prevents this process. After generation of the radical cation (RC), formation of a molecular complex (MC) between 1 and 2a-c initiates a stepwise mechanism, with attack of the sulfur atom of 1 to the aryl-conjugated position of 2a-c. Subsequent ring closure is the rate-determining step of these cycloadditions. Methoxy or dimethylamino substitution at the aryl group, while stabilizing the corresponding RC, results in a less exothermic formation of MC and a significant increase of the cycloaddition barrier.
Organic Letters | 2008
Inmaculada Andreu; Julio Delgado; Amparo Espinós; Raúl Pérez-Ruiz; M. Consuelo Jiménez; Miguel A. Miranda
Cycloreversion of cis- and trans-1,2,3-triphenylazetidine (c-2 and t-2) is achieved by electron transfer to (tris(4-bromophenyl)aminium radical cation (5 (*+)). Stepwise C-N and C-C bond cleavage of azetidine radical cations leads to cis- and trans-stilbene, together with N-benzylideneaniline, as final products. Mechanistic evidence is provided by quenching studies, using laser flash photolysis to generate 5 (*+) from its neutral precursor.
Chemical Communications | 2010
Alberto Soldevilla; Raúl Pérez-Ruiz; Yrene Díaz Miara; Axel G. Griesbeck
The fluorescence of caged phthalimide-serine couples 2 and 4 is up/down modulated by decarboxylative photorelease with fluorescence decrease (2) vs. moderate fluorescence increase (4) serving as reporter function.
Journal of Fluorescence | 2010
Raúl Pérez-Ruiz; Robert Fichtler; Yrene Díaz Miara; Matthieu Nicoul; Dominik Schaniel; Helfried Neumann; Matthias Beller; Dirk Blunk; Axel G. Griesbeck; Axel Jacobi von Wangelin
The photophysical properties of a series of structurally related 4-aminophthalimides and the corresponding 5-aminophthalic hydrazides (luminols) are reported. Absorption, steady-state, and time-resolved fluorescence spectra of luminols exhibited substitution, solvent, and pH dependence. Singlet lifetimes have been determined by time-resolved laser flash spectroscopy. UV spectra in gas phase and DMSO solution were calculated by TD-DFT which revealed the existence of two low-energy excited singlet states with strong pH-sensitivity.
Organic Letters | 2012
Raúl Pérez-Ruiz; José Antonio López Sáez; Luis R. Domingo; M. Consuelo Jiménez; Miguel A. Miranda
Oxidative electron transfer cycloreversion of trans,trans-2-cyclopropyl-4-methyl-3-phenyloxetane, using triphenylthiapyrylium perchlorate as a photosensitizer, leads to distonic 1,4-radical cations; subsequent cleavage gives rise to fragmentation products (pathway a), whereas nucleophilic trapping by acetonitrile affords a ring expanded oxazine (pathway b).
Photochemistry and Photobiology | 2014
Daniel Limones-Herrero; Raúl Pérez-Ruiz; Maria Consuelo Jiménez; Miguel A. Miranda
Cyamemazine (CMZ) is a neuroleptic drug that mediates cutaneous phototoxicity in humans. Here, the photobehavior of CMZ has been examined within α1‐acid glycoproteins, β‐ and γ‐cyclodextrins and SDS micelles. In all these microenvironments, CMZ emission was enhanced and blue‐shifted, and its lifetime was longer. Irradiation of the entrapped drug at 355 nm, under air; led to the N,S‐dioxide. Within glycoproteins or SDS micelles the reaction was clearly slower than in phosphate buffered solution (PBS); protection by cyclodextrins was less marked. Transient absorption spectroscopy in PBS revealed formation of the triplet state (3CMZ*) and the radical cation (CMZ+•). Upon addition of glycoprotein, the contribution of CMZ+• became negligible, whereas 3CMZ* dominated the spectra; in addition, the triplet lifetime became considerably longer. In cyclodextrins, this occurred to a lower extent. In all microheterogeneous systems, quenching by oxygen was slower than in solution; this was most remarkable inside glycoproteins. The highest protection from photooxidation was achieved inside SDS micelles. The results are consistent with photooxidation of CMZ through photoionization and subsequent trapping of the resulting radical cation by oxygen. This reaction is extremely sensitive to the medium and constitutes an appropriate probe for localization of the drug within a variety of biological compartments.
Organic Letters | 2013
Daniel Limones-Herrero; Raúl Pérez-Ruiz; M. Consuelo Jiménez; Miguel A. Miranda
Reductive photodehalogenation of chloroaromatics is assumed to proceed from the triplet excited state, although its energy is often insufficient to promote a clean homolytic C-Cl cleavage. A clear-cut experimental proof is provided that correlates self-quenching of the directly observed triplet excited states of chlorocarbazole-based dyads 1 and 2 with photoreactivity via intramolecular charge transfer.