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

• , it was already known that the intermolecular hydrogen bonding with solvent molecules may hinder the photoisomerization of indigo derivatives [46]. Nagasawa and co-workers found that the photoisomerization of 9a was inhibited by polar DMF due to formation of weak hydrogen bonds with formyl groups

Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors

• Abimelek Cortes-Pacheco,
• María Adelina Jiménez-Arellanes,
• Francisco José Palacios-Can,
• José Antonio Valcarcel-Gamiño,
• Rodrigo Said Razo-Hernández,
• María del Carmen Juárez-Vázquez,
• Adolfo López-Torres and
• Oscar Abelardo Ramírez-Marroquín

Beilstein J. Org. Chem. 2020, 16, 1277–1287, doi:10.3762/bjoc.16.108

• located between Ala189, Leu188, and Leu187, with energy values of −2.36 and −1.60 kcal/mol (Figure 5b). Compound 5 exhibited two weak hydrogen bonds from an OEt oxygen atom to an amide hydrogen atom of Ala189 and Leu188 (Figure 5c). The energy value was −0.89 kcal/mol, and the O–N distance was 3.24 Å. The

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• possessed the same stacking direction (along the a axis) by CH∙∙∙π interactions (C16∙∙∙C23, C16∙∙∙C19, C29∙∙∙C3, C29∙∙∙C15), while connected to the columns with opposite stacking direction via CH∙∙∙O type weak hydrogen bonds (C13∙∙∙O1) along the c axis (Figure 2c). 5b also gave the mixture of the two

Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding

• Stiliyana Pereva,
• Valya Nikolova,
• Silvia Angelova,
• Tony Spassov and
• Todor Dudev

Beilstein J. Org. Chem. 2019, 15, 1592–1600, doi:10.3762/bjoc.15.163

• “open” configuration the primary hydroxy groups do not participate in intramolecular hydrogen bond interactions. Relatively weak hydrogen bonds are formed between the secondary hydroxy groups in the wider/lower rim of the molecule. The calculations reveal that the “head–tail” arrangement of the narrow

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• ring with 3’-OH of the next unit. The second layer is twisted by ≈54° to the first layer and both layers are hold together by weak hydrogen bonds between O4 and methylene groups C9 and C11. In a particular layer the triazole rings are stacked. The same is true for the base moieties. For comparison, the

The phenyl vinyl ether–methanol complex: a model system for quantum chemistry benchmarking

• Dominic Bernhard,
• Fabian Dietrich,
• Mariyam Fatima,
• Cristóbal Pérez,
• Hannes C. Gottschalk,
• Axel Wuttke,
• Ricardo A. Mata,
• Martin A. Suhm,
• Melanie Schnell and
• Markus Gerhards

Beilstein J. Org. Chem. 2018, 14, 1642–1654, doi:10.3762/bjoc.14.140

• . Observing the intermolecular contacts, which may or may not be designated as weak hydrogen bonds but are expected to stabilize the complexes, the main difference between the two structures is a phenyl vs ethenyl CH to methanol O contact (cf. dashed gray lines in Figure 1). Both are separated by only a few

• hydrogen bonds; Introduction The balance of different noncovalent interactions is crucial for chemical and biochemical processes as it controls molecular recognition and aggregation [1][2][3][4][5][6]. In order to gain a deeper understanding of these processes, knowledge on exact structural arrangements

• electronically excited (S1) state is analyzed, in which a destabilization of the OH∙∙∙O structure compared to the S0 state is observed experimentally and theoretically. Keywords: dispersion interactions; IR spectroscopy; quantum-chemical calculations; rotational spectroscopy; structure determination; weak

London dispersion as important factor for the stabilization of (Z)-azobenzenes in the presence of hydrogen bonding

• Andreas H. Heindl,
• Raffael C. Wende and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2018, 14, 1238–1243, doi:10.3762/bjoc.14.106

• hydrogen bonding. As a result, all azobenzenes despite 7 showed comparable isomerization half-lives in DMSO. Accordingly, LD interactions can be responsible for the slightly but significantly prolonged half-lives compared to azodiamine 7. Analyzing the isomerization in 1,4-dioxane, weak hydrogen bonds as

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• the possible formation of weak hydrogen bonds in this solvent [44]. For both metal ions similar absorption features were observed. Upon addition of HgCl2 solution, the absorption maxima located at 378 nm and 431 nm are merging into a new band at 421 nm upon mercury complex formation. A progressive

Synthesis and characterization of the cyanobenzene-ethylenedithio-TTF donor

• Sandrina Oliveira,
• Dulce Belo,
• Isabel C. Santos,
• Sandra Rabaça and
• Manuel Almeida

Beilstein J. Org. Chem. 2015, 11, 951–956, doi:10.3762/bjoc.11.106

• can favour specific intermolecular interaction at the molecular periphery, either coordinating to other metals as found in other TTF type ligands or promoting weak hydrogen bonds. Results and Discussion Synthesis and structure of CNB-EDT-TTF The synthesis of CNB-EDT-TTF 3 was obtained under a general

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• direct conjugation with the tetrathiafulvalene chromophore. The crystal packing of the arylated monopyrrolotetrathiafulvalenes is primarily defined by networks of C–H···X weak hydrogen bonds and short S···S contacts involving the tetrathiafulvalene moieties. Keywords: cyclic voltammetry; N-arylation

• directed weak hydrogen bonds as well as C–H···π and S···S interactions. Addition of new parallel layers, connected to the previous layers via dispersive interactions of the van der Waals type, can be assumed to be a much slower process, leading to plate like crystals that mimic the layered makeup at the

• molecules interconnected by multiple weak hydrogen bonds, C–H···π, and S···S close contacts. Crystal packing of 4d viewed along the b axis. Molecules of 4d form layers parallel to the (001) plane being interconnected with each other by means of short S···S contacts (green) and C–H···O2N weak hydrogen bonds

Binding mode and free energy prediction of fisetin/β-cyclodextrin inclusion complexes

• Bodee Nutho,
• Wasinee Khuntawee,
• Chompoonut Rungnim,
• Piamsook Pongsawasdi,
• Peter Wolschann,
• Alfred Karpfen,
• Nawee Kungwan and
• Thanyada Rungrotmongkol

Beilstein J. Org. Chem. 2014, 10, 2789–2799, doi:10.3762/bjoc.10.296

• with the O2 and O3 atoms at the secondary rim of β-CD. In complex I, the O3' atom on B-ring was able to make weak hydrogen bonds with both oxygen atoms O2 and O3 at the wider rim, but in complexes II and III they slightly interacted with the O6 at the narrower rim instead. In addition, a weak hydrogen

Five-membered ring annelation in [2.2]paracyclophanes by aldol condensation

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2014, 10, 2021–2026, doi:10.3762/bjoc.10.210

• bridge angles and narrowed sp2 ring angles at the bridgehead atoms, and boat-shaped six-membered rings with the bridgehead atoms lying out of the plane of the other four atoms (see Table 2 below). The crystal packing involves two classical and three "weak" hydrogen bonds (two involving the

The crystal structure of the Dess–Martin periodinane

• Albert Schröckeneder,
• Desiree Stichnoth,
• Peter Mayer and
• Dirk Trauner

Beilstein J. Org. Chem. 2012, 8, 1523–1527, doi:10.3762/bjoc.8.172

• two weak hydrogen bonds of the type C13-H13A…O4 (green dashed bonds in Figure 3). In terms of graph-set analysis [20], the resulting 16-membered ring may be assigned a R22(16) descriptor. The dimers themselves are linked by two weak hydrogen bonds of the type C9–H9A…O4 (blue dashed bonds in Figure 3

• of ten atoms including two donor atoms and only one acceptor atom. There are two additional weak hydrogen bonds, which link adjacent molecules by cyclic centrosymmetric hydrogen-bond systems (Figure 4). A 16-membered ring with a R22(16) descriptor is established by involvement of the iodoxolone

A surprising new route to 4-nitro-3-phenylisoxazole

• Henning Hopf,
• Aboul-fetouh E. Mourad and
• Peter G. Jones

Beilstein J. Org. Chem. 2010, 6, No. 68, doi:10.3762/bjoc.6.68

• and parallel to the short y axis (Figure 2) by “weak” hydrogen bonds H12···O2 2.56 and H5···O3 2.39 Å. A suggested mechanism for the formation of 4 is outlined in Scheme 2. We propose that the nitro compound 4 is generated via the intermediate 6. This, in turn, could be generated by dehydration of the

Low temperature enantiotropic nematic phases from V-shaped, shape-persistent molecules

• Matthias Lehmann and
• Jens Seltmann

Beilstein J. Org. Chem. 2009, 5, No. 73, doi:10.3762/bjoc.5.73

• crystallise, thus making detailed studies of these phases extremely difficult. Therefore, low temperature stable (enantiotropic) phases are urgently demanded. In an earlier theoretical work, weak hydrogen bonds were suggested to possibly induce and stabilise biaxial nematic phases [27]. Therefore, we modified