Aggregation-induced emission effect on turn-off fluorescent switching of a photochromic diarylethene

• Luna Kono,
• Yuma Nakagawa,
• Ayako Fujimoto,
• Ryo Nishimura,
• Yohei Hattori,
• Toshiki Mutai,
• Nobuhiro Yasuda,
• Kenichi Koizumi,
• Satoshi Yokojima,
• Shinichiro Nakamura and
• Kingo Uchida

Beilstein J. Org. Chem. 2019, 15, 2204–2212, doi:10.3762/bjoc.15.217

• was dropped to the UV light irradiated crystal 1o (Supporting Information File 3, Movie 2). The rate of fluorescence quenching (τ1/2 is less than 0.2 s) in the crystalline state is much faster than those observed in solutions. This is attributed to the degree of condensation which is much higher in

• ), acetonitrile (orange line). The absorption at the excited wavelength of each solution was adjusted to 0.05. (emission peaks at 740 nm is attributed to the 2nd order diffracted excitation light.) (a) The energy diagram of the ESIPT process of 1. (b) ESIPT fluorescence quenching upon UV light (λ = 313 nm

• solutions (λex = 370 nm). (c) The fluorescence quenching of THF 100 vol % (water 0 vol %) solution at 670 nm (broken line) and that of THF/water = 10:90 (v/v) at 585 nm (solid line) upon UV irradiation. (a) Crystals of 1o before UV light irradiation, (b) Green fluorescence of 1o observed under UV light (λ

2,3-Dibutoxynaphthalene-based tetralactam macrocycles for recognizing precious metal chloride complexes

• Li-Li Wang,
• Yi-Kuan Tu,
• Huan Yao and
• Wei Jiang

Beilstein J. Org. Chem. 2019, 15, 1460–1467, doi:10.3762/bjoc.15.146

• maximum of 1 is located at 350 nm (Figure S22, Supporting Information File 1). It is known that the binding of metal ions could cause fluorescence quenching through photo-induced electron transfer [44]. Indeed, the fluorescence intensity of 1 is quenched gradually upon addition of TBA[AuCl4] (Figure 6a

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

• ground-state complex, with drastic changes in both, band shapes and intensities. The calculated rate constant of PET is faster than that of fluorescence and intersystem crossing, which makes it a more favorable deactivation pathway of the first excited singlet state leading to both fluorescence quenching

• solutions benefiting from the high affinities and the corresponding drastic fluorescence quenching, which is desirable from the viewpoints of economy, sensitivity and interference [8][26]. With regard to the treating application, high affinities with PSs avoid undesired off-target leaking during its

• employed (Table 1), indicating its privileged ability to form stable inclusion complexes with a variety of guest molecules. As for Fl, EY, RB, TPPS, AlPcS4 and TPS, a drastic complexation-induced fluorescence quenching without wavelength shifting was observed, which was assumed as the PET mechanism. 2,6

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• , quenching performance can be contributed to the energy transfer between ions and the materials [26]. Meanwhile, the UV–vis absorption peaks of CCDs exhibited no shift and regeneration before and after Fe3+ sensing, indicating that the fluorescence quenching is not resulted from the formation of new

• nm, Em. 5 nm. Fluorescence quenching degrees of a) CCDs and b) CN-dots in the presence of different metal ions. The concentrations of metal ions were 400 μМ. c) Fluorescence spectra of a CCDs system in the presence of different concentrations of Fe3+ ions (0–500 μM). d) Linear curve of the relative

Self-assembly behaviors of perylene- and naphthalene-crown macrocycle conjugates in aqueous medium

• Xin Shen,
• Bo Li,
• Tiezheng Pan,
• Jianfeng Wu,
• Yangxin Wang,
• Jie Shang,
• Yan Ge,
• Lin Jin and
• Zhenhui Qi

Beilstein J. Org. Chem. 2019, 15, 1203–1209, doi:10.3762/bjoc.15.117

• -assembly behavior in various solvents was investigated particularly in aqueous medium, due to the recently discovered hydrophilic properties of B21C7 crown macrocycle. An unexpected fluorescence quenching phenomenon was observed in the PDI-B21C7 macrocycle conjugate in chloroform. The detailed UV–vis

• their UV–vis absorption and fluorescence properties. An unexpected fluorescence quenching phenomenon was observed in the PDI-B21C7 macrocycle conjugate in chloroform. Through TEM characterization, it was illustrated that in aqueous medium, both PDI and NDI derivatives containing crown ether units could

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• with a possible character of TICT [55], which could explain a dual-fluorescence and fluorescence quenching in the high polarity media. The charge transfer nature of the transitions for the compounds 8c and 11c, compared to reference compounds 8a and 11a, was confirmed by quantum chemical calculations

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• stability under various conditions, particularly under physiological conditions. Although most BODIPYs are insensitive to pH changes, pH-activatable optical probes for cancer imaging have been reported, in which an aniline substituent in the meso-position of the BODIPY core led to efficient fluorescence

• quenching by photoinduced electron transfer (PET), whereas the protonated form was brightly fluorescent [31]. We report herein the synthesis and photophysical characterization of BODIPY derivatives with an aniline substituent in the meso-position to which different anchor groups have been attached, and we

Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene

• Jie Gao,
• Zhe Zheng,
• Lin Shi,
• Si-Qi Wu,
• Hongwei Sun and
• Dong-Sheng Guo

Beilstein J. Org. Chem. 2018, 14, 1840–1845, doi:10.3762/bjoc.14.157

• , we employed fluorescein (Fl) as the reporter dye according to our previously published result [26]. Fl of high brightness is strongly encapsulated into the GC5A cavity (Ka = 5.0 × 106 M−1), accompanied with a drastic complexation-induced fluorescence quenching (Ifree/Ibound = 37). Taken together

Investigations of alkynylbenziodoxole derivatives for radical alkynylations in photoredox catalysis

• Yue Pan,
• Kunfang Jia,
• Yali Chen and
• Yiyun Chen

Beilstein J. Org. Chem. 2018, 14, 1215–1221, doi:10.3762/bjoc.14.103

• benziodoxole have opposite effects for the radical alkynylation, we first conducted the fluorescence quenching experiments of tolylacetylenic benziodoxole derivatives 3a–f and found none of them oxidatively quenched the photoexcited Ru(bpy)32+* complex (see Supporting Information File 1, Scheme S1). We next

Carbohydrate inhibitors of cholera toxin

• Vajinder Kumar and
• W. Bruce Turnbull

Beilstein J. Org. Chem. 2018, 14, 484–498, doi:10.3762/bjoc.14.34

• tryptophan fluorescence quenching assay to show that octavalent lactose-based dendrimer 34 (Figure 16) had a Kd value of 33 µM as compared to monovalent lactose derivative having a Kd value of 18,000 µM [51]. Hence, compound 34 displayed 545 fold more potency per lactose unit than monovalent lactose. In

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• monomer–excimer switching approaches have some advantages over fluorescence quenching because of the large Stokes shifts and the ability to measure the signals at two different wavelengths, thereby providing a means for self-referencing. Furthermore, unlike the fluorophore-quencher beacons, the FRET and

• dT in the DNA strand with comparable affinity to that for A, and the base pairing resulted in fluorescence quenching. While the quenching of 2-AP can be useful for probing the structure and dynamics of the PNA and its DNA/RNA hybrids, the quenching effect is small and not highly specific as quenching

• was accompanied by fluorescence quenching, and Vg-modified aegPNA has been used to probe the interaction between RNA quadruplexes and PNA [181]. Another example of a nucleobase with extended conjugation that has been incorporated into PNA is 1,3-diaza-2-oxophenothiazine (tC), which is a tricyclic

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• antagonist) and the fluorescence intensity of 25 and its tetraacylated counterpart was comparable with the fluorescence of the labeling reagent alone. Aggregation-mediated fluorescence quenching was not observed which confirmed the advantage of application of highly hydrophilic linker molecules and non

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• indicating the interception of an excited CD state by the Fe3+ ion that leads to fluorescence quenching. The group exemplified the applicability of the material by demonstrating the ability of the B-CD to sense Fe3+ in tap water samples with a limit of detection of 242 nM, which complies with U.S

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

• a complex formation, namely a hypochromic effect and red shift of the absorption as well as fluorescence quenching upon addition of the host (Figure 6 and Supporting Information File 1, Figure S3). Furthermore, the significant line broadening of the absorption bands occurs most likely due to

Formose reaction accelerated in aerosol-OT reverse micelles

• Makoto Masaoka,
• Tomohiro Michitaka and
• Akihito Hashidzume

Beilstein J. Org. Chem. 2016, 12, 2663–2667, doi:10.3762/bjoc.12.262

• the cases of AOT and CTAB, the radius of the water pools (Rw) was evaluated by dynamic light scattering, whereas, in the case of TX, Rw was estimated by the fluorescence quenching technique. As can be seen in Supporting Information File 1, Figure S1, Rw for AOT and CTAB is almost proportional to the

Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu²⁺

• Rahman Hosseinzadeh,
• Mohammad Nemati,
• Reza Zadmard and
• Maryam Mohadjerani

Beilstein J. Org. Chem. 2016, 12, 1749–1757, doi:10.3762/bjoc.12.163

• a pronounced selectivity towards Cu2+ over other mono and divalent ions. The formation of the complex between L and Cu2+ was evaluated by absorption, fluorescence and 1H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon

• when excited at 280 nm. Upon addition 10 equiv of Cu2+ to the MeCN solution of sensor L, a remarkable fluorescence quenching was observed (Figure 4). In order to explore the selectivity of sensor L, similar experiments were carried out in the presence of other perchlorate salts of Cu2+, Hg2+, Pb2+, Zn2

• considerable fluorescence variations in comparison with L, and addition of Cu2+ ions to the corresponding solutions resulted in fluorescence quenching. Therefore, L can recognize Cu2+ even in the presence of other metal ions in acetonitrile solution. 1H NMR titration of L with Cu2+ In order to understand the

Synthesis of a deuterated probe for the confocal Raman microscopy imaging of squalenoyl nanomedicines

• Eric Buchy,
• Branko Vukosavljevic,
• Maike Windbergs,
• Dunja Sobot,
• Camille Dejean,
• Simona Mura,
• Patrick Couvreur and
• Didier Desmaële

Beilstein J. Org. Chem. 2016, 12, 1127–1135, doi:10.3762/bjoc.12.109

• fluorochrome in LDC nanoparticles can be used as far as the colloidal stability of the nanocarrier is preserved, but cannot address the intracellular tracking of the loaded drug after carrier disassembling. Thus, specific tools such as fluorescence resonance energy transfer (FRET) and fluorescence quenching

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• ][22][23][24][25]. We refrained from using additional donor functionalities such as the amino group, because we observed in a previous work that these substituents cause significant fluorescence quenching and lead to only weakly fluorescent derivatives [14]. Herein, we report the synthesis of novel 3

New synthetic strategies for xanthene-dye-appended cyclodextrins

• Milo Malanga,
• Andras Darcsi,
• Mihaly Balint,
• Gabor Benkovics,
• Tamas Sohajda and
• Szabolcs Beni

Beilstein J. Org. Chem. 2016, 12, 537–548, doi:10.3762/bjoc.12.53

• completely suppressed and the fluorescence, under irradiation at 366 nm, decreases substantially. This behavior is in agreement with the formation of the nonfluorescent lactone form under acidic conditions [12]. The lactone formation is mainly responsible for the fluorescence quenching of the dye. The UV–vis

Supramolecular chemistry: from aromatic foldamers to solution-phase supramolecular organic frameworks

• Zhan-Ting Li

Beilstein J. Org. Chem. 2015, 11, 2057–2071, doi:10.3762/bjoc.11.222

• chloroform and polar DMF (Figure 2). This finding was supported by 1H NMR, UV–vis, and fluorescence quenching studies. As expected, the folding state became more compact for longer sequences, which possess more donor–acceptor interacting sites. UV–vis experiments indicated that the folding state remained

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• -methylumbelliferone displays a strong absorption at 360 nm and a broad emission around 446 nm (Figure 4a). The fluorescence quantum yield is high (fluo = 81%) as previously determined under similar conditions [74]. In order to record the efficiency of the fluorescence quenching of the anion of 4-methylumbelliferone

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

• Natalia A. Danilkina,
• Petr S. Vlasov,
• Semen M. Vodianik,
• Andrey A. Kruchinin,
• Yuri G. Vlasov and
• Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

• and a sila-Sonogashira coupling as the polycondensation technique. The fluorescence of the cinnoline-containing polymers in THF was highly sensitive to quenching by Pd2+ ions. Keywords: cinnolines; fluorescence quenching; Pd2+ detection; poly(arylene ethynylene)s; Sonogashira coupling; Introduction

• (Figure 10 and Figure 11). For quantitative evaluation of the fluorescence quenching the parameter Q was used (Q = Io/I – 1, where Q, Io and I are the quenching efficiency, the initial fluorescence intensity and the fluorescence intensity after the interaction with a quencher, respectively). Figure 8 and

• and n = 6 for 10b) contribute considerably to the interaction between the palladium and oligomer molecules in the ground (non-excited) state. However, at the same time, the fluorescence quenching efficiency exhibited almost a two fold increase for the PAE 10b (Q = 47) in comparison with the PAE 10a (Q

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• sensitive to major erroneous ds-DNA sites (e.g., abasic sites) [91]. Namely, by using the well-known system of EB-fluorescence quenching by 7-deazaguanine incorporated within modified oligonucleotides, it showed that the abasic site (S) either one base pair away (DNA1-XY and DNA2-XY) or two base pairs away

• (DNA3-XY and DNA4-XY) from the EB chromophore showed an enhanced fluorescence quenching compared to the matched duplexes [91]. Among many studies of charge transfer in DNA, several applying ethidium bromide, revealed an unexpected complexity of the process, pointing out the importance of the DNA/EB

• be attributed to the ethidium exocyclic amines enabling by electron donation a non-radiative decay of phenanthridinium excited state, rather more likely than the previously proposed mechanism of water-induced deprotonation of phenanthridinium exocyclic amines, causing excited chromophore fluorescence

Preparation and evaluation of cyclodextrin polypseudorotaxane with PEGylated liposome as a sustained release drug carrier

• Kayoko Hayashida,
• Taishi Higashi,
• Daichi Kono,
• Keiichi Motoyama,
• Koki Wada and
• Hidetoshi Arima

Beilstein J. Org. Chem. 2014, 10, 2756–2764, doi:10.3762/bjoc.10.292

• disruption effects on DOX/LP and DOX/PEG-LP. Hereafter, a fluorescence quenching experiment should be performed to obtain the additional evidences that LP structure is kept after the PPRX formation. Preparation of CD PPRXs with DOX/PEG-LP On the basis of the results of Figure 1, we prepared PPRX of DOX/PEG

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• fluorescence data that showed lower fluorescence quenching by unbuffered anions as compared to that of phosphate species [30]. A much faster rate of RF photodegradation has been observed for sulfate anions than for phosphate anions (Figure 6) due to a strong complex formation, better electronegative character

• also supported by the fluorescence quenching of the two anions which were almost similar at pH 7.0 from 0.2–1.0 M. In spite of faster rate, the ratios of CDRF/LC were higher for phosphate (0.74) than for sulfate (0.48) suggesting an increased formation of LC directly from the excited singlet state in