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

• 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

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

• three amino acids. DPPIII participates in intracellular protein catabolism, which functions in pain modulation and oxidative stress. These biological functions make DPPIII a valuable target for drug development. Interestingly, although excimer emission was quenched, the pyrene monomer's emission was

• significantly solvent and pH-dependent. Namely, excimer fluorescence was mostly quenched in methanol, where the monomer fluorescence was also very low. Further, excimer fluorescence was quenched in acidic conditions and increased upon pH increase. Also, excimer emission was quenched upon heating without

• spectra could be caused both by a decrease in DNA helicity or by the uniform orientation of the dye concerning the chiral axis. Dye Phen-Py-1 bound to dipeptidyl peptidase (DPPIII) enzyme mutant E451A with high affinity and showed an interesting spectroscopic response: the excimer emission was totally

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

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

• 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

• pyrene excimer weaker emission at 520 nm. In presence of β-tryptase (0–20 nM), the monomer emission increases significantly while excimer emission disappears (Figure 8A). The enhancement of the pyrene monomer fluorescence confirms the involvement of the pyrenes in the β-tryptase binding. The monomer

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

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

• , the fluorescence intensity of the G2 monomer emissions gradually decreased, while the maximum emission intensity at around 485 nm (typical excimer emissions of pyrene) increased. The excimer emission band of G2 can be attributed to the interaction of two pyrene units resulting in intermolecular π–π

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

Fluorogenic PNA probes

• Tirayut Vilaivan

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

• detection of DNA by duplex [54] or triplex [69] formation have been demonstrated. Alternatively, the pyrene label can be placed onto the PNA backbone as a base replacement (in aegPNA) [55] or as a tethered label through a flexible linker (in acpcPNA) [70]. In most cases, excimer emission is predominant in

• the single stranded probe, and hybridization with the DNA target resulted in an increased monomer emission with a simultaneous decrease in the excimer emission. A switching ratio of >30 upon hybridization with the correct DNA target was obtained with double-pyrene-labeled acpcPNA probes [70

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

• 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

• cooling to 0 °C the IM/IEX ratio is increased to 100:30 (Figure 4, green curve) and at 77 K in a solid EPA [25] matrix the excimer emission completely disappears (Figure 4, blue curve). This behavior underlines the above-mentioned dynamic character of the excimer and suggests that the conformer 32a-STR is

Pyrene-modified PNAs: Stacking interactions and selective excimer emission in PNA₂DNA triplexes

• Alex Manicardi,
• Lucia Guidi,
• Alice Ghidini and
• Roberto Corradini

Beilstein J. Org. Chem. 2014, 10, 1495–1503, doi:10.3762/bjoc.10.154

• sequence with prevalence of pyrimidine bases, complementary to cystic fibrosis W1282X point mutation were synthesized. These compounds showed sequence-selective switch-on of pyrene excimer emission in the presence of target DNA, due to PNA2DNA triplex formation, with stability depending on the number and

• alone, and in the presence of DNA no clear-cut transition was detected, suggesting a pyrene-mediated strong aggregation of the probe itself. As described below, all the probes showed excimer emission in the 460–480 nm range upon hybridization (Figure 2). The temperature dependence of the excimer band in

• pyrene units, showed a weak excimer emission, due to weak self-association (this band tend to disappear with dilution, see Supporting Information File 1, Figure S16), which underwent a dramatic enhancement when PNA2 was bound to DNA1, whereas it remained unchanged by addition of DNA2 (Figure 2b and

Columnar/herringbone dual crystal packing of pyrenylsumanene and its photophysical properties

• Binod Babu Shrestha,
• Shuhei Higashibayashi and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2014, 10, 841–847, doi:10.3762/bjoc.10.80

• -shifted relative to those of 3 and pyrene, again owing to the π-extension. The emission of pyrene at 395 nm in solution is considered to result from the monomer form because of the low concentration, since pyrene is known to generate excimer emission at 480 nm at high concentrations (>10−5 M) [26][27

• ]. The emission of 1 at 422 nm is also assigned to monomer emission. Compound 1 did not generate excimer emission in solution concentrations over the range of 10−4–10−7 M and, due to the poor solubility of this compound, spectra at concentrations above 10−4 M could not be acquired. The emissions of 1 and

Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

• Ritesh Nandy and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2010, 6, 992–1001, doi:10.3762/bjoc.6.112

• and also by substituting donor-acceptor groups along the conjugation [23][24][25]. In addition, pyrene also exhibits excimer emission at a longer wavelength compared to monomer emission which can be used in sensing applications [26][27][28][29][30]. The pyrene chromophore can act as a donor or as an

Quinoline based receptor in fluorometric discrimination of carboxylic acids

• Kumaresh Ghosh,
• Suman Adhikari,
• Asoke P. Chattopadhyay and
• Purnendu Roy Chowdhury

Beilstein J. Org. Chem. 2008, 4, No. 52, doi:10.3762/bjoc.4.52

• fluororeceptors 1 and 2 have been designed and synthesized for detection of hydroxy carboxylic acids in less polar solvents. The receptor 1 shows monomer emission quenching followed by excimer emission upon hydrogen bond-mediated complexation of carboxylic acids. The excimer emission distinguishes aromatic

• dicarboxylic acids from aliphatic dicarboxylic acids and even long chain aliphatic dicarboxylic acids from short chain aliphatic dicarboxylic acids. The receptor 1 is found to be selective for citric acid with a strong excimer emission in CHCl3. On the contrary, the receptor 2 exhibited less binding constant

• value and did not form any excimer upon complexation with the same acids under similar conditions. This established the role of quinoline ring nitrogen in binding with the acids. Keywords: carboxylic acid recognition; excimer emission; naphthalene; quinoline; Introduction The sensing and monitoring of