Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• , indigo exists in a planar E-form, which is more stable than the overcrowded and non-planar Z-form (Figure 6a) [23]. Irradiation of E-indigo, however, does not result in the photoisomerization into the Z-form due to the rapid proton transfer occurring in the excited state (ESPT) from the N atom towards

• , findings from the de Melo group confirmed that the photoisomerization of compound 17a was a result of the absence of ESPT, in contrast to the mono-Boc substituted indigo derivative which exhibited ESPT [65]. Photochromic N,N'-diarylindigos N,N'-Diarylindigos, a sub-type of N,N'-disubstituted indigos

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• observed for the excited-state proton transfer (ESPT) of so-called photoacids. The latter are weak acids in the ground state, whereas their acidity in the excited state increases significantly [25][26][27]. As the activity of photoacids is triggered by light, they have a great potential to be employed as

• ][34]. The change of acidity, however, depends on the actual complex structure. For example, it was demonstrated in a comparative study of 2-naphthol and a hydroxyflavylium derivative that the ESPT is suppressed upon complexation with CB[7] if the hydroxy functionality is embedded deeply in the host

• cavity. In contrast, if the hydroxy group of the ligand points far outside the binding pocket of CB[7] the ESPT is comparable to the one observed with the non-complexed ligand [28]. Recently, we discovered that the 8-hydroxybenzo[b]quinolizinium ion (1a, Figure 1) represents an efficient water-soluble

Fluoride-driven ‘turn on’ ESPT in the binding with a novel benzimidazole-based sensor

• Kai Liu,
• Xiaojun Zhao,
• Qingxiang Liu,
• Jianzhong Huo,
• Bolin Zhu and
• Shihua Diao

Beilstein J. Org. Chem. 2015, 11, 563–567, doi:10.3762/bjoc.11.61

• , College of Chemistry, Tianjin Normal University, Tianjin, 300387, China 10.3762/bjoc.11.61 Abstract A novel fluorescence sensor (BIP) bearing NH and OH subunits displayed a highly selective and sensitive recognition property for fluoride over other anions. Fluoride-driven ESPT, poorly used in anion

• recognition and sensing, was suggested to be responsible for the fluorescence enhancement with a blue shift of 35 nm in the emission spectrum. Keywords: anion recognition; deprotonation; ESPT; fluoride; ‘turn on’ fluorescence; Introduction Design and synthesis of selective and efficient sensors for various

• proton transfer (ESPT), as an extensively exploited mechanism in many biological and chemical processes, has been employed poorly in anion recognition and sensing [2][11][12][13][14][15][16]. In the ESPT molecules, a five or six-membered intramolecular hydrogen-bonded ring formed, and a proton/hydrogen