Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• , ΦΔ are much larger, up to 100% in dichloromethane (DCM) and ACN, likely due to the heavy-atom effect. Electrochemistry study The redox potentials of the dyads were studied with cyclovoltammetry (Figure 6, Table 3), and the Gibbs free energy changes of the charge separation (ΔGCS) and charge

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• −, and ClO4− (tetrabutylammonium salts were used as anion source) were also tested tentatively by fluorescence titration (Figure 5). The overwhelming majority of aromatic molecules follow the heavy-atom effect rule [48]. However, it was surprisingly found that the coordination of selected anions, such as

• halide ions, especially the heavier iodide ion, to the macrocyclic sensor, slightly enhanced the fluorescence emission in CH2Cl2/CH3OH 4:1 (v/v) at 298 K, instead of quenching the fluorescence as predicted by the classic heavy-atom effect. The corresponding fluorescence enhancement efficiency of selected

• −1. In another perspective, the presence of the coordination of selected anions to the macrocyclic sensor enhanced the fluorescence emission in various degree, extremely contrary to the classic heavy-atom effect caused by a heavy atom. In general, this macrocyclic sensor showed high fluorescence

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• . The quantum yields were calculated based on Equation 1. where R means reference and S sample, respectively. Generally weak fluorescence emissions were observed for the thiophene-based chromophores due to a remarkable spin–orbit coupling which is originating from the heavy atom effect of sulfur [73][74

Heterogeneous photocatalysis in flow chemical reactors

• Christopher G. Thomson,
• Ai-Lan Lee and
• Filipe Vilela

Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125

Development of fluorinated benzils and bisbenzils as room-temperature phosphorescent molecules

• Shigeyuki Yamada,
• Takuya Higashida,
• Yizhou Wang,
• Masato Morita,
• Takuya Hosokai,
• Kaveendra Maduwantha,
• Kaveenga Rasika Koswattage and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 1154–1162, doi:10.3762/bjoc.16.102

• restriction of intramolecular motions [23]. Moreover, crystalline 2,5-dihexyloxy-4-bromobenzaldehyde displays green phosphorescence, which stems from rapid ISC due to the heavy atom effect via halogen bonding (C=O···Br) [24]. Moreover, benzophenone- or benzil-type molecules can achieve long-lived

Towards triptycene functionalization and triptycene-linked porphyrin arrays

• Gemma M. Locke,
• Keith J. Flanagan and
• Mathias O. Senge

Beilstein J. Org. Chem. 2020, 16, 763–777, doi:10.3762/bjoc.16.70

• transferred to the nickel porphyrin, which subsequently quenches the fluorescence due to the heavy atom effect that is characteristic of nickel [48]. These initial results suggest that an energy/electron transfer is taking place, as the strong emission of the excited zinc porphyrin that was observed for the

Dimerization reactions of aryl selenophen-2-yl-substituted thiocarbonyl S-methanides as diradical processes: a computational study

• Michael L. McKee,
• Grzegorz Mlostoń,
• Katarzyna Urbaniak and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 410–416, doi:10.3762/bjoc.13.44

• isolated from the reaction mixture. Thus, the presence of the heteroatom is of crucial importance for this new type of dimerization of aryl/hetaryl thiocarbonyl S-methanides of type 1 and this fact reflects the importance of so called ‘heavy atom effect’ [15] in the studied system. Stepwise, diradical

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• enhance the potential of the nanocarrier. Results and Discussion Adamantane-substituted squaraine (AdSq) was synthesized in a three step synthesis. Benzothiazole rings were introduced to enlarge the π-system. The sulfur atoms of these moieties increase the intersystem crossing due to the heavy atom effect

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• –5 vs entry 6). However, the yield of 2 decreased in the series Cl → Br → I (2b–e, Table 2, entries 2–5), which was probably a manifestation of the internal photochemical heavy-atom effect [60]. The presence of bromo- or iodo-substituents in the substrates 1c–e increases the probability of

Synthesis of new, highly luminescent bis(2,2’-bithiophen-5-yl) substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole

• Anastasia S. Kostyuchenko,
• Vyacheslav L.Yurpalov,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2014, 10, 1596–1602, doi:10.3762/bjoc.10.165

• increasing atomic number of the heteroatom of the azole unit is a clear manifestation of the heavy atom effect [35]. The proximity and availability of higher energy 3d levels in sulfur facilitates radiationless relaxation modes of the excited electron. Enhanced spin–orbit coupling opens up intersystem

Topochemical control of the photodimerization of aromatic compounds by γ-cyclodextrin thioethers in aqueous solution

• Hai Ming Wang and
• Gerhard Wenz

Beilstein J. Org. Chem. 2013, 9, 1858–1866, doi:10.3762/bjoc.9.217

• by an increase in the relative amount of the anti isomer. The increases of both the quantum yield and amount of the anti product – called the heavy atom effect – was attributed to an increased population of triplet states [29][30][31]. Heavy atoms close to the excited entity accelerate the rate of

• there are several explanations for the observed anti specificity: (a) ACE is tightly surrounded by the seven sulfur atoms of host 3, which may lead to an increased population of the triplet state and consequently to a heavy atom effect, which favors the formation of the anti dimer. Other CD derivatives

• atom effect of the S-atoms of CD derivatives 1–7 should facilitate intersystem crossing to the triplet state and therefore support the formation of the anti-HH dimer. Because this preference does not hold true in this case, especially for host 2, the multiplicity of the excited state seems not to be

Electron self-exchange activation parameters of diethyl sulfide and tetrahydrothiophene

• Martin Goez and
• Martin Vogtherr

Beilstein J. Org. Chem. 2013, 9, 1448–1454, doi:10.3762/bjoc.9.164

• ], with evidence for a noticeable increase in the presence of DES by an intermolecular heavy-atom effect [33]) is quenched [34] quantitatively (lifetime, 10 μs [32]; diffusion-controlled electron transfer from DES [35]) under our experimental conditions. Protonation of the pyranyl radical TPP• is unknown

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• intersystem crossing by the heavy-atom effect, and thus decreases the singlet excited-state lifetime of the arene. Mattay considered this as direct proof that the addition of benzene to 1,3-dioxoles takes place primarily via the singlet excited-state of benzene. Ferree et al. had earlier provided evidence

Fluorometric recognition of both dihydrogen phosphate and iodide by a new flexible anthracene linked benzimidazolium-based receptor

• Kumaresh Ghosh and
• Debasis Kar

Beilstein J. Org. Chem. 2011, 7, 254–264, doi:10.3762/bjoc.7.34

• ][42][43][44][45]. Iodide binding induced quenching of emission is attributed to the i) complementarity in size of iodide with the pseudocavity formed by the receptor-binding site and ii) heavy atom effect of iodide, which is also true for Br−. But the small quenching of emission in the presence of Br

• − suggests that I− induced quenching is not only due to the heavy atom effect but also involves some hydrogen bonding effects. Figure 12 is the Stern–Volmer plot of the quenching process. It was also noted that while the monomeric benzimidazolium unit 2 was ineffective in CH3CN, it showed measurable changes

Heavy atom effects in the Paternò–Büchi reaction of pyrimidine derivatives with 4,4’-disubstituted benzophenones

• Feng-Feng Kong,
• Jian-Bo Wang and
• Qin-Hua Song

Beilstein J. Org. Chem. 2011, 7, 113–118, doi:10.3762/bjoc.7.16

• 1c) is enthalpy–entropy controlled. A heavy atom effect is suggested to be responsible for these unusual phenomena based on the triplet-diradical mechanism of the Paternò–Büchi reaction. Keywords: benzophenone; heavy atom effect; Paternò–Büchi reaction; regioselectivity; triplet diradical

• leading to substantial control of regio- and stereoselectivity [5][6][7][8][9][10][11][12][13]. The “heavy atom effect” is a term which has been used to describe the influence of “heavy atom” substitution on a spin-forbidden transition such as various intersystem crossings. If heavy atoms are present in a

• observations with those of systems of 1a (with electron-donating groups, EDGs), and 1b and 1f (also with EWGs). However, as a heavy atom effect, observations above can be rationalized based on the triplet mechanism of the Paternò–Büchi reaction. Results and Discussion Substituent effects To investigate