Mechanistic investigations of polyaza[7]helicene in photoredox and energy transfer catalysis

• Johannes Rocker,
• Till J. B. Zähringer,
• Matthias Schmitz,
• Till Opatz and
• Christoph Kerzig

Beilstein J. Org. Chem. 2024, 20, 1236–1245, doi:10.3762/bjoc.20.106

• as the ionization product resulting from a consecutive two-photon absorption at the selected high laser intensity [69][70], yielding the corresponding long-lived radical cation with second-order decay that is typical for oxidized/reduced species, and a solvated electron as by-product. The latter is

• contrast to all previous measurements, no signal of the Aza-H radical cation generated through two-photon absorption is detected. This can be easily rationalized as the radical cation is most likely rapidly quenched by TsNa (compare the proposed reaction mechanism regenerating the oxidized catalyst). That

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

Dyes in modern organic chemistry

• Heiko Ihmels

Beilstein J. Org. Chem. 2019, 15, 2798–2800, doi:10.3762/bjoc.15.272

• , two-photon absorption probes or chemosensors [24][25][26][27][28][29][30]. After all, dye chemistry is literally an "evergreen" in scientific research, and consequently, its significant contributions to scientific developments and breakthroughs is well-documented in several Nobel prizes that are

A photochemical determination of luminescence efficiency of upconverting nanoparticles

• Baptiste Amouroux,
• Clément Roux,
• Jean-Claude Micheau,
• Fabienne Gauffre and
• Christophe Coudret

Beilstein J. Org. Chem. 2019, 15, 2671–2677, doi:10.3762/bjoc.15.260

• lanthanides’ spectroscopic properties (regular level spacing and long excited states lifetimes), one emitting ion can undergo several energy transfer processes before relaxing radiatively [15], making the overall process fundamentally different form second harmonic generation or two-photon absorption

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• electron-transfer phenomena or two-photon absorption [32][33][34][35][36]. As part of our research program we have developed arylisoquinolines that integrate a boronic acid ester [37][38][39] or a BMes2 unit [6][40]. The presence of the boron-substituent confers interesting photophysical properties to

Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

• Alessandro Iagatti,
• Baihao Shao,
• Alberto Credi,
• Barbara Ventura,
• Ivan Aprahamian and
• Mariangela Di Donato

Beilstein J. Org. Chem. 2019, 15, 2438–2446, doi:10.3762/bjoc.15.236

• , belonging to the hydrazone family. The outstanding properties of this molecule, involving fluorescence toggling, bistability, high isomerization quantum yield and non-negligible two-photon absorption cross section, make it very promising for numerous applications. Here we show that the light induced Z/E

• fluorescence techniques with the aim of better characterizing the actinic step of its operation. Furthermore, we employ time resolved spectroscopy to evaluate the two-photon absorption cross section of the molecule and, by comparing the results with those previously obtained using a fluorescence method, we

• the excited state lifetime. Two-photon excitation Earlier experiments revealed that hydrazone 1 is able to isomerize also upon two-photon excitation [29]. In the present study we used transient absorption spectroscopy as an alternative method to determine the two-photon absorption cross section of the

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• the mechanism of action of anticancer compounds, and for safer photodynamic therapy. Keywords: bioimaging; dendrimer; fluorescence; phosphorus; two-photon absorption; Introduction Natural luminescence phenomena such as the bioluminescence of fireflies or of certain marine microorganisms, or the

• widespread popularity of TPE (also named TPA, for two-photon absorption) in the biology community, with on one side, the advent of two-photon excitation fluorescence microscopy [4], even for research clinical uses [5], and on the other side with the discovery of the TPA properties of quantum dots (inorganic

• classical fluorophores in their structure, have been already synthesized [13]. Besides, some types of dendrimers have shown non-traditional intrinsic luminescence, i.e., luminescence in the absence of known fluorophores [14]. Dendrimers functionalized with fluorophores having two-photon absorption

Complexation of a guanidinium-modified calixarene with diverse dyes and investigation of the corresponding photophysical response

• Yu-Ying Wang,
• Yong Kong,
• Zhe Zheng,
• Wen-Chao Geng,
• Zi-Yi Zhao,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2019, 15, 1394–1406, doi:10.3762/bjoc.15.139

• photons as the excitation source. The fluorescent probe simultaneously absorbs two low energy photons to reach the excited state followed by fluorescence [57]. Acedan (6-acetyl-2-(dimethylamino)naphthalene) is a well-known probe with two-photon absorption that has been utilized in two-photon microscopy

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• ]. Moreover, some DPP derivatives also showed aggregation induced emission (AIE) [13][14] and the ability to selectively sense fluoride ions [26][27][28]. The modern era of DPP chromophores has been opened by Gryko et al. [3][11][12][18][20][21][29] who have demonstrated their large and tunable two-photon

• absorption cross-section (δ2PA) generally ranging from 100–2500 GM, but for instance DPPs end-capped with imidazolium [21] or dendritic thiophenes [16] showed δ2PA of 4000 and 7000 GM, respectively. However, to the best of our knowledge, the third-harmonic generation (THG) NLO process has not been

Synthesis and spectroscopic properties of 4-amino-1,8-naphthalimide derivatives involving the carboxylic group: a new molecular probe for ZnO nanoparticles with unusual fluorescence features

• Laura Bekere,
• David Gachet,
• Vladimir Lokshin,
• Wladimir Marine and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2013, 9, 1311–1318, doi:10.3762/bjoc.9.147

• (3H)-yl)benzoic acid (4) was found to be a sensitive molecular probe for ZnO nanoparticles. We investigated in detail one- and two-photon absorption properties of this fluorophore. In nonpolar solvents, the acid 4 absorbs at about 400 nm and fluoresces at 500 nm with a fluorescence lifetime of about 7

• patterns. Keywords: fluorescence; hydrogen bond; 1,8-naphthalimide; one- and two-photon absorption; zinc oxide; Introduction 1,8-Naphthalimide derivatives are useful for a variety of applications owing to their strong fluorescence, electroactivity and photostability. These compounds can be employed as

• concentration. A Stern–Volmer plot shows a simultaneous static and dynamic quenching, probably superimposed with FRET between pure acid 4 and the anionic complex, formed in ethanol. The full analysis of the formation of these complexes will be published elsewhere. The two-photon absorption cross section of 4 in