Electrosynthetic access to unsymmetrical oxaza[8]helicenes with high chiral stability and strong circularly polarized luminescence (CPL)

• Tin Zar Aye,
• Rubal Sharma,
• Muthu Karuppasamy,
• Daiya Suzuki,
• Haruka Nakajima,
• Yoshitane Imai,
• Mitsuhiro Arisawa,
• Mohamed S. H. Salem and
• Shinobu Takizawa

Beilstein J. Org. Chem. 2026, 22, 372–382, doi:10.3762/bjoc.22.25

• Heterohelicenes are compelling chiral π-conjugated scaffolds for optoelectronic and chiral-photonic technologies because their helical frameworks and doped heteroatoms endow them with various photophysical, chiroptical, and electronic merits. However, unsymmetrical heterohelicenes remain rare, as their synthesis

• ) relative to their oxaza[7]helicene analogues (<25 kcal/mol). After chiral HPLC separation, the enantiomers display mirror-image CD and strong solution CPL, with |glum| up to 2.6 × 10−3 and fluorescence brightness up to 30.75 M−1 cm−1. Keywords: chemoselectivity; chiroptical; circular dichroism

• chiral stability, typically strengthening chiroptical responses [27][28][29]; however, it also escalates synthetic difficulty due to heightened strain and more demanding regio- and chemoselective construction. While [7]helicenes have been extensively explored, their [8]helicene counterparts remain

Non-central chirality in organic chemistry

• Ken Tanaka and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2026, 22, 370–371, doi:10.3762/bjoc.22.24

• ; chiroptical properties; molecular chirality; Chirality is a foundational concept in organic chemistry, traditionally framed around tetrahedral carbon stereocenters. Over the past decades, however, it has become increasingly clear that molecular handedness is not confined to localized points in space. Axes

• remote from the reaction site. Second, non-central chiral frameworks remain fertile ground for catalyst design, not only as derivatives of established motifs but also as newly conceived architectures that redefine how chirality can be embedded into catalytic systems. Third, the pronounced chiroptical and

Screwing the helical chirality through terminal peri-functionalization

• Devesh Chandra,
• Sachin and
• Upendra Sharma

Beilstein J. Org. Chem. 2026, 22, 205–212, doi:10.3762/bjoc.22.14

• components in organic field effect transistors (OFETs), molecular wires, and chiral conductive materials [19][20][21]. Furthermore, helicenes are widely explored in chiroptical sensing, molecular recognition, and supramolecular self-assembly, enabling the construction of next generation responsive materials

Design and synthesis of an axially chiral platinum(II) complex and its CPL properties in PMMA matrix

• Daiki Tauchi,
• Sota Ogura,
• Misa Sakura,
• Kazunori Tsubaki and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2026, 22, 143–150, doi:10.3762/bjoc.22.7

• two platinum(II) chromophore units, leading to the chiroptical properties in the MLCT region through exciton coupling under restricted molecular motion. Keywords: axial chirality; chiral chemistry; circularly polarized luminescence (CPL); phosphorescence; platinum(II) complex; Introduction

• -derived pendant group, which exhibited aggregation-enhanced red phosphorescence and CPL properties in the solid states [20], while Yam and co-workers also reported pincer-type platinum(II) complexes containing chiral amine moieties, and investigated their aggregation behavior and chiroptical properties

• [22]. In both cases, significant CPL signals were observed only in the aggregated state, because the introduction of chirality through point chirality does not induce a significant electronic effect in the monomeric state; instead, the observed chiroptical activity originates from the chiral spatial

Rotaxanes with integrated photoswitches: design principles, functional behavior, and emerging applications

• Jullyane Emi Matsushima,
• Khushbu,
• Zuliah Abdulsalam,
• Udyogi Navodya Kulathilaka Conthagamage and
• Víctor García-López

Beilstein J. Org. Chem. 2025, 21, 2345–2366, doi:10.3762/bjoc.21.179

• dual orthogonal manipulation of the rotaxane’s conformational regulation and chiroptical switching properties. Thus, this system functions as a phototriggered chiral on–off switch in polar aprotic solvents. These types of rotaxanes hold promise for developing simple information storage materials and

• -bonded to a chiral peptide station. This rotaxane works as a chiroptical switch by light-induced macrocycle movement along the axle [65]. The need to understand the photochemistry of fumaramides to aid their usage in various applications led to the design of rotaxanes containing different axles. Both

A m-quaterphenyl probe for absolute configurational assignments of primary and secondary amines

• Yuka Takeuchi,
• Mutsumi Kobayashi,
• Yuuka Gotoh,
• Mari Ikeda,
• Yoichi Habata,
• Tomohiko Shirai and
• Shunsuke Kuwahara

Beilstein J. Org. Chem. 2025, 21, 2211–2219, doi:10.3762/bjoc.21.168

• , exciton-coupled CD has emerged as a powerful chiroptical method, providing a non-empirical correlation between the sign of the Cotton effect and the spatial arrangement of the electric transition dipole moments of interacting chromophores [7]. More recently, CD-based chiroptical probes have been developed

• configurations of chiral amines were determined. Reported chiroptical probes for determining the absolute configuration of chiral compounds only used the sign of the Cotton effect in CD. This method uses not only the sign but also the intensity of the Cotton effect in CD to determine the absolute configuration

Synthesis of N-doped chiral macrocycles by regioselective palladium-catalyzed arylation

• Shuhai Qiu and
• Junzhi Liu

Beilstein J. Org. Chem. 2025, 21, 1917–1923, doi:10.3762/bjoc.21.149

• yields (ΦF up to 0.69). Furthermore, enantiomeric resolution of inherent chiral MC1 was achieved using preparative chiral HPLC, enabling detailed investigation of its chiroptical behavior through circular dichroism and circularly polarized luminescence spectroscopy. Keywords: dihydroindolocarbazole

• , these macrocycles show blue to green emissions with high fluorescence quantum yields (ΦF up to 0.69). Owing to the existence of inherent chirality, two enantiomers of N-doped macrocycle MC1 were successfully isolated by chiral resolution, enabling detailed investigation of its chiroptical properties

• fraction was assigned as the (−)-enantiomer. As shown in Figure 5, the CD spectra displayed mirror images with positive and negative Cotton effects at wavelengths from 250 to 500 nm, indicating strong chiroptical responses. (+)-MC1 shows five positive Cotton effects at 259, 305, 355, 392, and 453 nm, as

Synthesis of optically active folded cyclic dimers and trimers

• Ena Kumamoto,
• Kana Ogawa,
• Kazunori Okamoto and
• Yasuhiro Morisaki

Beilstein J. Org. Chem. 2025, 21, 1603–1612, doi:10.3762/bjoc.21.124

• chiral [2.2]paracyclophane-containing enantiopure ribbon-shaped compounds as the chiral monomers. Unicursal π-conjugated systems were folded at the [2.2]paracyclophane units, and exhibited good photoluminescence quantum efficiencies and CPL anisotropy factors. Opposite chiroptical properties were

• above, the experimental CD and CPL signs of (Sp)-6 and (Sp)-7 were reproduced by the TD-DFT calculations. Molecular orbitals of (Sp)-6 involved in the CPL are obviously curved and twisted, resulting in the opposite chiroptical signs. Twisted chirality is known to result in CPL of π-conjugated molecules

• | values of the ordered of 10–4–10–3. The chiroptical properties of dimers and trimers showed opposite Cotton effects and CPL signals, despite the same absolute configuration of the planar chiral [2.2]paracyclophane crossing points. The π-conjugation system of the dimer that exhibited CPL was highly curved

Wittig reaction of cyclobisbiphenylenecarbonyl

• Taito Moribe,
• Junichiro Hirano,
• Hideaki Takano,
• Hiroshi Shinokubo and
• Norihito Fukui

Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107

• racemization barrier. Optical and chiroptical properties The UV–vis absorption spectra of CBBC 1, mono-olefin 3, and bis-olefin 5 are shown in Figure 5a. The absorption of 3 tails to 370 nm, which is comparable to the absorption end of CBBC 1. On the other hand, the absorption of bis-olefin 5 is blue-shifted

Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications

• Meng Qiu,
• Jing Du,
• Nai-Te Yao,
• Xin-Yue Wang and
• Han-Yuan Gong

Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106

• systems – has granted access to increasingly complex helicene frameworks with well-defined chirality. This review systematically summarizes recent advancements in the synthesis, structural engineering, and chiroptical performance of nitrogen-doped helicenes and their heteroatom-doped derivatives

• , emphasizing their potential as next-generation chiral optoelectronic materials and outlining future directions toward multifunctional integration and quantum technological applications. Keywords: azahelicene; chiroptical properties; circularly polarized luminescence (CPL); heteroatom containing

• – particularly those incorporating additional heteroatoms within the helical π-conjugated framework – remains lacking. This review addresses this gap by systematically summarizing recent advances (from the past five years) in the synthesis, structural modification, and chiroptical properties of nitrogen-doped

Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes

• Bartłomiej Pigulski

Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99

• or green colours of 157–159 and azulene-like weak absorption due to S0→S1 transition. Strong chiroptical responses were revealed by ECD spectra, with the maximum |gabs| values reaching 0.022 (at 421 nm) and 0.021 (at 427 nm) for 158, and 159, respectively. These values are among the highest |gabs

Photochemically assisted synthesis of phenacenes fluorinated at the terminal benzene rings and their electronic spectra

• Yuuki Ishii,
• Minoru Yamaji,
• Fumito Tani,
• Kenta Goto,
• Yoshihiro Kubozono and
• Hideki Okamoto

Beilstein J. Org. Chem. 2025, 21, 670–679, doi:10.3762/bjoc.21.53

• ]. Also, the effects of fluorination on the chiroptical features of [n]helicenes were theoretically predicted [41]. In addition to the manipulation of electronic natures, partial fluorination of PAHs has been recognized to be significant for crystal design and engineering. Thus, molecular packing patterns

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• becoming increasingly relevant also in medicine. Many axially chiral compounds are important as catalysts in asymmetric catalysis or have chiroptical properties. This review overviews recent progress in the synthesis of axially chiral compounds via asymmetric organocatalysis. Atroposelective

4,6-Diaryl-5,5-difluoro-1,3-dioxanes as chiral dopants for liquid crystal compositions

• Maurice Médebielle,
• Peer Kirsch,
• Jérémy Merad,
• Carolina von Essen,
• Clemens Kühn and
• Andreas Ruhl

Beilstein J. Org. Chem. 2024, 20, 2940–2945, doi:10.3762/bjoc.20.246

• chemistry [1][2][3]. In particular, cholesteric, i.e., chiral nematic, liquid crystals (LCs) are attractive for many display applications due to their chiroptical characteristics as well as the selective reflection of light giving rise to Bragg interference colors [4]. Cholesteric LCs can be obtained either

• enantiomers (R,R)-3/(S,S)-3, (R,R)-4/(S,S)-4 were obtained by slow evaporation from n-heptane solution and structures were determined by X-ray diffraction, which allowed the correlation of the chiroptical properties with the configuration (Figure 2 and Figure 3). The HTP of all enantiomers were measured with

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

• chiroptical properties with a large change in the absorption spectra and a bathochromic shift in the emission maximum. This system represents a rare example of a multi-output readout system, showing responses in ECD, fluorescence, and CPL activity. The authors later reported a similar system with a bipyridine

• switching unit that exhibits similar chiroptical switching properties [50]. During the writing of this review, Lee et al. reported molecular tweezers presenting an allosteric response with hard–soft cooperativity [51]. Tweezers 19 is based on a terpyridine ligand substituted in a 6,6” position by azacrown

Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

• with TCNQ in dichloromethane at room temperature afforded 50 with an impressive yield of 84%. Chiroptical properties Push–pull chromophores synthesized through the [2 + 2] CA–RE reaction can, in certain cases, exhibit distinct chiroptical properties, attributable to their nonplanar geometry and steric

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• to the molecules which cannot be superimposed on their own mirror image. Nanomaterials with chiroptical properties have shown potential applications in different fields such as optical devices, polarization-based information encryption, circularly polarized luminescence (CPL) lasers, or biosensing

• [20][21][22][23][24]. Currently, there is a great interest in the introduction of chirality into large conjugated polyaromatics to obtain chiral NGs with chiroptical properties. Among these chiral NGs, helicenes represent the dominant chiral compounds by virtue of their inherent helical chirality [25

• final Scholl cyclodehydrogenation of 85 afforded the HBC-trimer 86. The non-linear optics of NG 86 and the chiroptical properties of enantiomers were well studied. The CPL spectra centered at 610 nm were observed for both enantiomeric forms and the glum was determined as 2 × 10−3. Due to large

Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds

• Alemayehu Gashaw Woldegiorgis and
• Xufeng Lin

Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185

• -catalyzed enantioselective transformations [9][14][22][23]. Axial chirality is also found in chiral stationary phases for enantioselective separation, dopants in liquid-crystalline materials, chiroptical molecular switches, microporous soluble polymers, and interlocked nanotubes (Figure 3) [24]. In addition

Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• and applied in practice [4][5][6]. Among them, the fluorescent materials emitting circularly polarized luminescence (CPL) have attracted intensive interest owing to their wide applications in various researching fields including 3D displays, chiroptical materials, and so on [7][8][9][10]. Circular

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• up to 67%, while their bandgaps and chiroptical responses could be tuned by twisting the bipyrrole chromophore. The solvatochromism and apparent superradiance of these chromophores indicated a potential involvement of solvent-induced symmetry-breaking charge transfer in the excited state [34]. Here

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• the development of new chiroptical materials. Such molecules, however, have hardly been investigated to date probably because of the synthetic difficulty to obtain them as pure enantiomers. There have been only a few reports for the binaphthyl-fused furan-ring construction from the C3-alkynylated

• -shifted than 4a despite such a sterically demanding group usually disturbs intermolecular stacking interactions. Subsequently, the chiroptical properties of the synthesized compounds were evaluated (Figure 2 and Figure 3, Table 2). The circular dichroism (CD) spectra in CHCl3 solutions showed apparent

A chiral self-sorting photoresponsive coordination cage based on overcrowded alkenes

• Constantin Stuckhardt,
• Diederik Roke,
• Wojciech Danowski,
• Edwin Otten,
• Sander J. Wezenberg and
• Ben L. Feringa

Beilstein J. Org. Chem. 2019, 15, 2767–2773, doi:10.3762/bjoc.15.268

• rotation upon irradiation with light [38][39][40]. Moreover, they can be used as chiroptical multistate switches to control various functions in areas such as catalysis [41][42][43], soft materials [43][44][45] and supramolecular chemistry [46][47]. Employing molecular motors as ligands in SCCs provides an

α-Photooxygenation of chiral aldehydes with singlet oxygen

• Dominika J. Walaszek,
• Magdalena Jawiczuk,
• Jakub Durka,
• Olga Drapała and
• Dorota Gryko

Beilstein J. Org. Chem. 2019, 15, 2076–2084, doi:10.3762/bjoc.15.205

• stereoselectivity was enforced by bulkier and electron-withdrawing groups as diarylprolinol silyl ether 18 (Table 1, entries 4 and 5). The absolute configuration of diastereoisomers formed was assigned using chiroptical spectroscopic methods (see section ‘Determination of the absolute configuration of the product

• its rather simple structure diol 6 was not previously reported in the literature. The ratio of stereoisomers 6 was determined by HPLC analysis while the absolute configuration of the newly created stereocenter was established using a chiroptical spectroscopic method. Samples of stereoisomers syn-6 and

Complexation of chiral amines by resorcin[4]arene sulfonic acids in polar media – circular dichroism and diffusion studies of chirality transfer and solvent dependence

• Bartosz Setner and
• Agnieszka Szumna

Beilstein J. Org. Chem. 2019, 15, 1913–1924, doi:10.3762/bjoc.15.187

• aromatic analytes afford strongly induced circular dichroism (ICD) signals in the near-UV and visible regions [18]. Endo-functionalized molecular tubes, first reported by the Glass group [19], were used by the Jiang group for molecular recognition and chiroptical sensing of epoxides in water. The absolute

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• absolute configurations of (R)-5 and (S)-4 were assigned by comparison of the chiroptical data with those reported [45]. The stereochemical outcome of the reaction is consistent with Kazlauskas’ empirical rule [51]. The conversion (% c) and the enantiomeric excess (E) values were calculated according to

• , and the optical rotation of 7a' were in conformity with those reported [54]. In addition, the 1,3-anti stereochemistry of the diol 7a was confirmed by converting it to the target compound 2, and comparing its chiroptical data with the reported values, as described afterwards. For the synthesis of 2