Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• with two bis-2,2’-bipyridyl ligands and bis-pyrene fluorescent units. The stable conformation of perhydroanthracene is with the two pyrene units in the equatorial position. Their close spatial proximity leads to the observation of an excimer emission. Upon Zn2+ coordination, the perhydroanthracene core

Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• excellent photoelectric properties such as strong emission, efficient excimer formation, and suitable intermolecular stacking for good charge carrier transport. They have been applied as active layer in OFETs with high ambipolar mobility due to their well-defined monocrystalline microstructures resulting

• -shifted in the film. These results indicate molecular π-stacking aggregation and excimer formation on the films [2]. The PL in film was obtained as a function of temperature (Figure 4). The observed reduction of the PL intensity on heating is expected for organic semiconductors due to self-quenching

• spin-coated films, the best fitting of the decay curves of 1 and 2 indicated three and two lifetimes, respectively. Compound 1 displayed a dominant and longer lifetime compared to solution, 25.9 ns (66.83%), attributed to excimer emission, which usually presents longer lifetimes compared to the

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• at 440 nm [64], TCTA at 410 nm [65], and TPBi at 390 nm [66]) and at longer wavelengths due to the excimer/exciplex emissions at the interfaces of NPB-TCTA/EML and EML/TPBi were observed, signifying that the OLED possessed a well-balanced electron and hole transport. Moreover, due to the efficient

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• a pH-dependent excimer formation that is significantly red-shifted relative to the pyrene and phenanthridine fluorescence. While the conjugate with a short linker showed negligible spectrophotometric changes due to the polynucleotide addition, the conjugate with a longer and more flexible linker

• in the cell membrane. Keywords: dipeptidyl peptidase enzyme; excimer; molecular dynamics simulations; phenanthridine; polynucleotide; pyrene; Introduction The design of small molecules that can selectively bind and discriminate different biomolecular structures (polynucleotides vs proteins, DNA or

• ]. Excimers are formed when pyrene moieties form supramolecular complexes by intermolecular or intramolecular π–π interactions, causing a significant shift of single pyrene bands to longer wavelengths. Pyrenes are often used as a sensor part of receptor molecules, so their excimer bands switch on/off to

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• way junctions. There was a four-fold increase in the intensity of the pyrene excimer signal observed when an oligonucleotide containing two incorporations of the double-headed nucleoside 41 hybridized with an RNA target whereas the pyrene–pyrene excimer band almost vanished when the oligonucleotide

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• intensities of absorption or emission at two wavelengths minimizes the error from the physical or chemical fluctuations in the sample. Conventional peptide probes based on environment-sensitive fluorophores [20][21][22], fluorescence resonance energy transfer (FRET) pairs [13] and pyrene excimer/monomer [23

• ]. The attachment of pyrenes to the termini of a flexible peptide linker results in a ratiometric fluorescent probe (Figure 1C). Upon interaction with a biomolecule, the distance between the pyrenes changes, subsequently their monomer to excimer and vice versa fluorescence signal changes. However, the

• fluorescent probes for nucleic acids detection. The first probe 2 is a pyrene-based peptide beacon containing two Trp–Thr–Lys tripeptide arms attached to a central lysine spacer (Figure 3A) [34]. Unbound peptide beacon 2 in folded form exhibits typical pyrene excimer emission at 490 nm. Peptide beacon 2

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• , internal conversion, intermolecular electron transfer, as well as excimer or exciplex formation and isomerization. These phenomena significantly limit the usability of luminogens for the abovementioned purposes. Several attempts were already made to prevent or restrict these non-radiative pathways by

Easy access to a carbohydrate-based template for stimuli-responsive surfactants

• Thomas Holmstrøm,
• Daniel Raydan and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2020, 16, 2788–2794, doi:10.3762/bjoc.16.229

• metal-binding event. This study was carried out by having pyrene fluorophores attached to the two non-chelating positions, giving rise to excimer fluorescence when the distance between them was decreased due to the ring flip [12]. Carbohydrates with gluco stereochemistry have also been used as templates

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• buffer and also in buffer containing 150 mM NaCl at physiological pH value. Furthermore, the multivalent aggregates demonstrated a significant selectivity in ATP detection over ADP, AMP and pyrophosphate. Keywords: amphiphile; ATP; excimer; multivalency; self-assembly; Introduction Supramolecular anion

• compact arrangement of the stacked pyrene chromophores and this restriction of internal motion might have resulted in a higher excimer intensity [71]. In order to see whether the presence of other phosphate analytes interfered in ATP detection, fluorescence enhancements of PBIm12 (75 µM), for only ATP (50

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• exhibits an emission maximum peak at 329 nm upon excitation at 294 nm. This emission band is probably due to the formation of the ground-state dimer by interaction between the benzene rings upon excitation or excimer emission caused by the interaction between the aromatic rings [41][43]. As the

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

• fluorescence quantum yields were determined with quinine sulfate as standard reference (Φfluo = 0.55 in 0.05 M H2SO4) [50][51]. The lifetimes were measured by time-correlated single-photon counting (Edinburgh instruments FLS 920). Laser-flash photolysis experiments were performed using a XeCl excimer laser

Host–guest interactions in nor-seco-cucurbit[10]uril: novel guest-dependent molecular recognition and stereoisomerism

• Xiaodong Zhang,
• Wei Wu,
• Zhu Tao and
• Xin-Long Ni

Beilstein J. Org. Chem. 2019, 15, 1705–1711, doi:10.3762/bjoc.15.166

• Xiaodong Zhang Wei Wu Zhu Tao Xin-Long Ni Key Laboratory of Macrocyclic and Supramolecular Chemistry of Guizhou Province, Guizhou University, Guiyang 550025, China 10.3762/bjoc.15.166 Abstract The unique monomer and excimer fluorescence emissions of pyrene were first exploited as distinctly

• , the top–center isomer of G2 within both host-1 and host-2 could be characterized because of the novel monomer and excimer photophysical property of pyrene as fluorophore. As a result, we demonstrated here a novel guest-controlled molecular recognition and stereoisomerism for the first time. Results

• of G1 in host-1 and host-2, despite the clear split of resonances corresponding to the protons on the hosts. A number of studies suggest that pyrene is one of the most useful fluorogenic units, being sensitive to conformational change because of its relatively efficient monomer and excimer emissions

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• enantiopure P5A-DPA and P5A-Py. It was found that the CD signals were enhanced by aggregation. P5A-DPA showed aggregation-induced emission enhancement, while P5A-Py showed aggregation-induced emission quenching, accompanied by excimer emission when aggregating in water and THF mixed solution. Keywords

• assigned to the excimer emission of Py (Figure S23, Supporting Information File 1) [54]. Conclusion Two new planar chiral macrocyclic hosts P5A-DPA and P5A-Py were synthesized by grafting two fluorophore pigments (DPA or Py) on pillar[5]arene through CuAAC “click” reaction. The new macrocyclic compounds

• the THF solution. P5A-DPA and P5A-Py showed an enhancement of the CD signals by adding water due to restriction of the conformers’ rotations by aggregation. P5A-DPA showed a fluorescence enhancement when less than 50% of water was added, while P5A-Py showed emission quenching and excimer emission when

Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

• Cristina Cebrián and
• Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

• phenyl ring. As the parent complex 23a, excimer formation via metal–metal interactions was observed for both derivatives at high concentrations or in neat films. Nevertheless, the increased conjugation within the chromophoric ligand led to a lower emission energy, which fell into the NIR region. The

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

Fluorogenic PNA probes

• Tirayut Vilaivan

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

• background and good response with DNA, as well as offering an excellent specificity [65]. In addition to fluorophore-quencher interactions, FRET [66] and pyrene monomer–excimer switching [67][68] have been employed as alternative mechanisms for inducing fluorescence changes in the DNA probes. The FRET and

• 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

• monomer–excimer switching beacons are also fluorescent in the unbound state, and therefore it is possible to monitor the success of cellular delivery. In the case of pyrene monomer–excimer switching, the long fluorescence lifetime of the pyrene excimers allows facile elimination of background signals from

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• detecting markers [14], as fluorescent DNA probes [15], non-covalent binders to canonical oligonucleotide templates [16], and antiviral agents [17][18]. Notably, pyrene excimer formation in DNA template assemblies is much less efficient than in normal pyrene conjugates due to the helical twist between

• mechanism of sensing involves Hg(II) ion coordination to two thymine moieties followed by pyrene excimer formation [19]. Furthermore, compound A2 and adenine derivative A3 were reported to act as fluorescent sensors for thymine and adenine [23]. To the best of our knowledge, pyrene–nucleobases have not been

Synthesis and supramolecular properties of regioisomers of mononaphthylallyl derivatives of γ-cyclodextrin

• Markéta Bláhová,
• Sergey K. Filippov,
• Lubomír Kováčik,
• Jiří Horský,
• Simona Hybelbauerová,
• Zdenka Syrová,
• Tomáš Křížek and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2017, 13, 2509–2520, doi:10.3762/bjoc.13.248

• also occur. Moreover to make the situation more complex, the change of the stoichiometry from 1:1 to 2:2 upon the increase in concentration has been reported for a naphthalene–β-CD complex; the concurrently observed increase in excimer indicated close pairing of naphthalene molecules [43]. Nevertheless

Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

• Jarosław Lewkowski,
• Maria Rodriguez Moya,
• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Renata Kontek and
• Gabriela Gajek

Beilstein J. Org. Chem. 2016, 12, 1229–1235, doi:10.3762/bjoc.12.117

• aminophosphonates. We have measured their electronic absorption and emission spectra in chloroform solution. Although photodecomposition of pyrene in this solvent has been reported [28], we found that this is not the case of the compounds under study. To avoid excimer formation, spectra were recorded at low sample

Biradical vs singlet oxygen photogeneration in suprofen–cholesterol systems

• Fabrizio Palumbo,
• Francisco Bosca,
• Isabel M. Morera,
• Inmaculada Andreu and
• Miguel A. Miranda

Beilstein J. Org. Chem. 2016, 12, 1196–1202, doi:10.3762/bjoc.12.115

• photolysis cell in right-angle geometry. An excimer laser (LEXTRA50 Lambda Physik) was used for the excitation at 308 nm (laser excitation at 5 low-pulse energies for each molecule). A 5 mm thick (5 cm in diameter) 1050 nm cut-off silicon filter and a 1270 nm interference filter were placed between the diode

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

• . Thus, I prepared compound 9, which bore a pyrene unit [17] (Scheme 4), based on previously published research by Sijbesma and co-workers, who had taken advantage of the excimer signal of the pyrene dimer to evaluate the stability of their famous quadruple hydrogen bonded 2-ureido-4[1H]-pyrimidinone

• dimers [18]. The excimer exhibits an emission band at 500–600 nm, which is separated from that of the monomer. I thus determined the Kdim of 9 as 3.0 × 107 M−1 in chloroform saturated with water ([water] ≈ 0.45 M) and 8.5 × 107 M−1 in freshly opened chloroform ([water] ≈ 17 mM). Dimer 8·8 had another

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• functionalizations in terminal positions. First applications were presented with pyrene, cinnamoyl and anthracenyl labelled ARs. Keywords: articulated rods; click chemistry; molecular rods; oligospiroketals; pyrene excimer; Introduction One of the basic principles in living nature is based on shape-persistent and

• and structureless excimer emission at ca. 477 nm is red-shifted by more than 100 nm against the structured monomer emission at ca. 377 nm. This conspicuous change in the fluorescence spectra permits the investigation of the equilibrium between 32a-STR and 32a-FOL (Scheme 11). At first we investigated

• the influence of temperature and solvent viscosity on the STR–FOL equilibrium. At room temperature a ratio between the monomer and excimer emission IM/IEX of about 100:60 is observed (Figure 4, red curve). The ratio does not change on dilution (1.5·10−5 mol/L → 1.1·10−6 mol/L) indicating that excimer

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

• position of the DNA-active chromophore in the peptide backbone as well as the structural characteristics of the linker between them can easily be modified. In the first series of peptide-bridged bis-phenanthridine derivatives, derivative 11 with the shortest linker formed an intramolecular excimer

• phenanthridine–thymine conjugates [77], intercalated into ds-DNA whereby binding was marginally influenced by attached thymine and the peptide backbone. More intriguing was the observed excimer fluorescence emission and the very specific CD spectrum of pentapeptide confirming the very efficient phenanthridine