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Publications 2022

2022
22022

Propagation Losses Estimation in a Cationic-Network-Based Hydrogel Waveguide

C. Pons, J. M. Galindo, J. C. Martín, I. Torres-Moya, S. Merino, M. A. Herrero, E. Vázquez, P. Prieto, J. A. Vallés

Micromachines 2022, 13, 2253

A method based on the photographic recording of the power distribution laterally diffused by cationic-network (CN) hydrogel waveguides is first checked against the well-established cut-back method and then used to determine the different contributions to optical power attenuation along the hydrogel-based waveguide. Absorption and scattering loss coefficients are determined for 450 nm, 532 nm and 633 nm excitation. The excellent optical loss values obtained (0.32–1.95 dB/cm), similar to others previously described, indicate their potential application as waveguides in different fields, including soft robotic and light-based therapies.

https://doi.org/10.3390/mi13122253

 

Donor–acceptor naphthalimides and peryleneimides for all-solution-processed thin film lasers

B. Donoso,  V. Bonal, I. Torres-Moya, P. G. Boj, J. A. Quintana, J. M. Villalvilla, J. Herrera, P. Prieto, M. A. Díaz-García

J. Mater. Chem. C, 2022, 10, 16004

Donor–Acceptor (D–A) naphthalimides (NI) are highly fluorescent multitask compounds that have demonstrated success in a variety of optoelectronic applications, among which, thin film organic lasers (TFOLs) are not included. Here we assess the potential of various NI derivatives for lasing applications by investigating their amplified spontaneous emission (ASE) properties when dispersed in polystyrene thin films. To overcome the relatively low ASE photostability measured in the NIs, a series of peryleneimides (PI) derivatives, with similar chemical structure but with more extended p-conjugation, is synthesized and reported here, together with a complete characterization of their optical and ASE properties, both in solution and thin film. Most investigated compounds show ASE, with emissions at different wavelengths spanning from the blue to the red, depending on the derivative. Furthermore, surface emitting TFOLs with top-layer polymeric distributed feedback resonators are fabricated and characterized. This work represents an advance in the field of low-cost TFOLs, by including two families of successful laser dyes, NIs and PIs, the latter with significantly better photostability

DOI: 10.1039/d2tc03081k

 

Stereoselective, Ruthenium-Photocatalyzed Synthesis of 1,2- Diaminotruxinic Bis-amino Acids from 4‑Arylidene-5(4H)‑oxazolones

S. Sierra, M. V. Gomez, A. I. Jiménez, A. Pop, C. Silvestru, M. L. Marín, F. Boscá, G. Sastre, E. Gómez-Bengoa, E. P. Urriolabeitia

J. Org. Chem. 2022, 87, 3529−3545

The irradiation of (Z)-2-phenyl-4-aryliden-5(4H)-oxazolones 1 in deoxygenated CH2Cl2 at 25 °C with blue light (465 nm) in the presence of [Ru(bpy)3](BF4)2 (5% mole ratio) as a triplet photocatalyst promotes the [2+2] photocycloaddition of the CC bonds of the 4-arylidene moiety, thus allowing the completely regio- and stereoselective formation of cyclobutanebis(oxazolone)s 2 as single stereoisomers. Cyclobutanes 2 have been unambiguously characterized as the μ-isomers and contain two E-oxazolones coupled in an anti-head-to-head form. The use of continuous-flow techniques in microreactors allows the synthesis of cyclobutanes 2 in only 60 min, compared with the 24−48 h required in batch mode. Ring opening of the oxazolone heterocycle in 2 with a base affords the corresponding 1,2-diaminotruxinic bis-amino esters 3, which are also obtained selectively as μ-isomers. The ruthenium complex behaves as a triplet photocatalyst, generating the reactive excited state of the oxazolone via an energy-transfer process. This reactive excited state has been characterized as a triplet diradical 3 (E/Z)-1* by laser flash photolysis (transient absorption spectroscopy). This technique also shows that this excited state is the same when starting from either (Z)- or (E)- oxazolones. Density functional theory calculations show that the first step of the [2+2] cycloaddition between 3 (E/Z)-1* and (Z)-1 is formation of the C(H)−C(H) bond and that (Z) to (E) isomerization takes place at the 1,4-diradical thus formed.

https://doi.org/10.1021/acs.joc.1c03092

 

Low energy loss (0.42 eV) and efficiency over 15% enabled by non-fullerene acceptors containing N-bis(trifluoromethyl)phenylbenzotriazole as the core in binary solar cells.

M. Privado, B. Donoso, K. Khandelwal, R. Singhal, F. G. Guijarro, A. Díaz-Ortız, P. Prieto, P. de la Cruz, G. D. Sharma, F. Langa

J. Mater. Chem. C, 2022, 10, 13174

Two non-fullerene acceptors, A–D–A0–D–A systems, with an identical central 2-(3,5-bis(trifluoromethyl)phenyl)-2H-benzo[d][1,2,3]triazole (CF3-BTA) (A0) connected with 4,4-bis (2-ethylhexyl)-4H-cyclopenta[[2,1-b]3,4-b0]dithiophene (CPDT) (D), to different end capped acceptor units, namely tricyanoethylene (TOCR1) and 2-(5,6-difluoro-3-oxo-2,3-dihydro-1H-inden-1-yldene)malononitrile (TOCR2) are prepared. These two materials were used as acceptors in polymer solar cells, along with two wide band-gap conjugated polymers, P1 or P2. Following optimization of the weight ratio variation and solvent vapor annealing process, the PSCs based on P1:TOCR1, P1:TOCR2, P2:TOCR1 and P2:TOCR2 demonstrated overall power conversion efficiency (PCE) of 10.31, 15.17, 11.88, and 5.89 percent with the highest value corresponding to P1:TOCR2 (15.17%). The high value of exciton dissociation and charge collection probability in P1:TOCR2 may explain the high PCE value. The lowest value of P2:TOCR2 based PSCs, on the other hand, is due to the low HOMO offset between TOCR2 and P2, which hinders exciton dissociation and hole transfer from TOCR2 to P2, as evidenced by the fact that the photoluminescence intensity of pristine TOCR2 is not fully quenched in the P2:TOCR2 blend, whereas the PL intensity of TOCR1 or TOCR2 is completely quenched in P1:TOCR1, P1:TOCR2 and P2:TOCR1 blends.

DOI: 10.1039/d2tc02289c

 

Radiationless mechanism of UV deactivation by cuticle phenolics in plants

A. González Moreno, A. de Cózar, P. Prieto, E. Domínguez, A. Heredia

Nature Plants 2022, 13, Article number: 1786

Hydroxycinnamic acids present in plant cuticles, the interphase and the main protective barrier between the plant and the environment, exhibit singular photochemical properties that could allow them to act as a UV shield. Here, we employ transient absorption spectroscopy on isolated cuticles and leaf epidermises to study in situ the photodynamics of these molecules in the excited state. Based on quantum chemical calculations on p-coumaric acid, the main phenolic acid present in the cuticle, we propose a model in which cuticle phenolics display a photoprotective mechanism based in an ultrafast and non-radiative excited state deactivation combined with fluorescence emission. As such, the cuticle can be regarded as the first and foremost protective barrier against UV radiation. This photostable and photodynamic mechanism seems to be universal in land plants giving a special role and function to the presence of different aromatic domains in plant cuticles and epidermises.

https://doi.org/10.1038/s41467-022-29460-9

volume 13, Article number: 1786 (2022)

Microwave Irradiation as a Powerful Tool for the Preparation of n-Type Benzotriazole Semiconductors with Applications in Organic Field-Effect Transistors

I. Torres-Moya, A. Harbuzaru, B. Donoso, P. Prieto, R. Ponce Ortiz, Á. Díaz-Ortiz.

Molecules2022, 27, 4340

In this work, as an equivocal proof of the potential of microwave irradiation in organic synthesis, a complex pyrazine-decorated benzotriazole derivative that is challenging to prepare under conventional conditions has been obtained upon microwave irradiation, thus efficiently improving the process and yields, dramatically decreasing the reaction times and resulting in an environmentally friendly synthetic procedure. In addition, this useful derivative could be applied in organic electronics, specifically in organic field-effect transistors (OFETs), exhibiting the highest electron mobilities reported to date for benzotriazole discrete molecules, of around 10−2 cm2V−1s−1.

https://doi.org/10.3390/molecules27144340

 

New insights about structure/optical waveguide behavior relationships in linear bisethynylbenzenes  

C. Tardío, J. Álvarez-Conde, I. Torres-Moya, A. M. Rodríguez, A. de la Hoz, J. Cabanillas-González, P. Prieto

J. Mater. Chem. C 2022, 10, 6411-6418

In order to establish a relationship between the structure and the optical waveguiding behavior, two series of linear bisethynylbenzenes combining trifluoromethyl and methoxy groups in the core and external rings were synthesized. The presence of the methoxy groups in the core benzene produced, generally, amorphous supramolecular aggregates, while the presence of trifluoromethyl groups in the core benzene produced needle shape crystals. As a result of this most planar compounds showed optical waveguiding behavior as shown by photoluminescence (PL) microscopy and optical loss coefficients down to 0.54x10-3 dB μm-1 in some of them, revealing optical waveguides assets. X-ray diffraction studies performed to establish a first approximation to the structure/optical property relationships confirming that the presence of channels in the crystal structure is concomitant with optical waveguiding behavior. This feature constitutes a relevant parameter to be taken into account to understand light propagation in these structure.

DOI: 10.1039/d2tc00173j

 

Benzotriazole-based multidonor-acceptor systems as attractive two-photon absorption dye platforms

S. Sierra, M. V. Gomez, A. I. Jiménez, A. Pop, C. Silvestru, M. L. Marín, F. Boscá, G. Sastre, E. Gómez-Bengoa, E. P. Urriolabeitia.

Dyes Pigments2022, 200, 110149

Pyrazine-decorated benzotriazole cores allow the orthogonal combination of two dipolar systems within a single molecule. A series of this type of derivatives was synthesized and their photophysical features were studied. The properties of these compounds showed remarkable differences in function depending on the substitution in the pyrazine ring of the benzotriazole core. Furthermore, the two-photon absorption property (2PA) was studied to determine the structure-properties relationship for the reported compounds. The best dye achieved a crosssection of 1532 GM, which was higher than values previously obtained for similar D-π-A-π-D benzotriazole derivatives. TD-DFT calculations, which supported the experimental observations, indicating the interaction between the two dipolar systems was responsible for enhancing the 2 PA properties and favoring bathochromic
shifts.

https://doi.org/10.1016/j.dyepig.2022.110149

 

Stereoselective, Ruthenium-Photocatalyzed Synthesis of 1,2- Diaminotruxinic Bis-amino Acids from 4‑Arylidene-5(4H)‑oxazolones

S. Sierra, M. V. Gomez, A. I. Jiménez, A. Pop, C. Silvestru, M. L. Marín, F. Boscá, G. Sastre, E. Gómez-Bengoa, E. P. Urriolabeitia 

J. Org. Chem. 2022

 

The irradiation of (Z)-2-phenyl-4-aryliden-5(4H)-oxazolones 1 in deoxygenated CH2Cl2 at 25 °C with blue light (465 nm) in the presence of [Ru(bpy)3](BF4)2 (5% mole ratio) as a triplet photocatalyst promotes the [2+2] photocycloaddition of the C═C bonds of the 4-arylidene moiety, thus allowing the completely regio- and stereoselective formation of cyclobutane-bis(oxazolone)s 2 as single stereoisomers. Cyclobutanes 2 have been unambiguously characterized as the μ-isomers and contain two E-oxazolones coupled in an anti-head-to-head form. The use of continuous-flow techniques in microreactors allows the synthesis of cyclobutanes 2 in only 60 min, compared with the 24–48 h required in batch mode. Ring opening of the oxazolone heterocycle in 2 with a base affords the corresponding 1,2-diaminotruxinic bis-amino esters 3, which are also obtained selectively as μ-isomers. The ruthenium complex behaves as a triplet photocatalyst, generating the reactive excited state of the oxazolone via an energy-transfer process. This reactive excited state has been characterized as a triplet diradical 3(E/Z)-1* by laser flash photolysis (transient absorption spectroscopy). This technique also shows that this excited state is the same when starting from either (Z)- or (E)-oxazolones. Density functional theory calculations show that the first step of the [2+2] cycloaddition between 3(E/Z)-1* and (Z)-1 is formation of the C(H)–C(H) bond and that (Z) to (E) isomerization takes place at the 1,4-diradical thus formed.

 

DOI: 10.1021/acs.joc.1c03092

 

Flow Chemistry in Drug Discovery

This book reviews the challenges and opportunities posed by flow chemistry in drug discovery, and offers a handy reference tool for medicinal chemists interested in the synthesis of biologically active compounds.

Prepared by expert contributors, the respective chapters cover not only fundamental methodologies and reactions, such as the application of catalysis, especially biocatalysis and organocatalysis; and non-conventional activation techniques, from photochemistry to electrochemistry; but also the development of new process windows, processes and reactions in drug synthesis. Particular attention is given to automatization and library synthesis, which are of great importance in the pharmaceutical industry. Readers will also find coverage on selected topics of general interest, such as how flow chemistry is contributing to drug discovery R&D in developing countries, and the green character of this enabling technology, for example in the production of raw materials for the pharmaceutical industry from waste.

Given its scope, the book appeals to medicinal chemistry researchers working in academia and industry alike, as well as professionals involved in scale-up and drug development.

 

Green Aspects of Flow Chemistry for Drug Discovery

 In: . Topics in Medicinal Chemistry. pp 23-70. Springer, Berlin, Heidelberg. 2022