Homochirality, the uniformity in single molecular handedness, is a defining feature of life. Although universal in biology, the evolutionary advantage of selecting one enantiomer over its mirror image remains unresolved. One possible clue may lie in catalysis itself: recent studies demonstrate that oxygen evolution reaction (OER), a key step in photosynthesis, is sensitive to chirality. Here, we report that electrochemical OER performance with chiral additives is determined by the alignment of their electric (ETDM) and magnetic (MTDM) transition dipole moments in the lowest-energy transition. Enantiomers with parallel ETDM–MTDM configurations consistently outperform their antiparallel counterparts. Notably, this bias also manifests in natural systems, suggesting a shared stereoelectronic principle. We define this stereoelectronic correlation as the Supplementary Angle Effect (SAE). Our findings establish SAE as a quantifiable descriptor for electrocatalysts and provide a conceptual basis for understanding the role of molecular handedness in catalysis and its possible evolutionary implications.

Push-pull organic compounds with pi-conjugated backbones are attracting considerable interest in terms of their highly efficient (NLO) non-linear optical effects. In this respect, cyano groups constitute one of the strongest electron acceptors suitable for NLO materials. We herein report the first 1,1,4,4-tetracyanobutadiene (TCBD) spirobifluorene (SBF) through a double [2+2] cycloaddition-retroelectrocyclization. Enantiomeric resolution by HPLC using a chiral stationary phase (CSP) and theoretical calculations unveiled not only the nature of the potential energy surface, but also the absolute configuration of each enantiomer. Since both the presence of strong donor and acceptor, as well as the intrinsic non-centrosymmetric character of chiral compounds are a prerequisite for the development of NLO properties, the first hyperpolarizability of the developed system was theoretically calculated. The results suggested a strong dependence on the conformation and an intensity enhancement for certain conformers of 1 as compared to its allenic TCBD analogue. Therefore, the present study opens a new class of SBF compounds suitable for NLO applications.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Spirobifluorenes are an important class of spiro compounds frequently used in the field of organic electronics. However, harnessing spiroconjugation to obtain high-performance in such structural motifs remains unexplored. We herein propose that peripheral functionalization may serve as a useful tool to control spiroconjugation in an ON/OFF manner on both chemical reactivity and photophysical properties. In particular, the ratio of mono- and di-functionalized spirobifluorenes found experimentally during their synthesis were found to be 3/2, 7/2, and 12/2 for phenyl, nitro-phenyl and amino-phenyl analogues, respectively. These remarkable reactivity differences correlate with the spiroconjugation character evaluated theoretically at the CAM-B3LYP/6-31G(d,p) level of theory. Additionally, comparison of experimental and predicted optical and chiroptical responses shows that spiroconjugated molecular orbitals have a significant or negligible involvement on the main electronic transitions depending on the peripheral functionality of the spirobifluorene.

Chiroptical spectroscopic methods serve as a practical tool for the structural characterization of chiral systems based on the interaction with polarized light. The higher sensitivity of these methods, compared with their achiral counterparts, not only enables the determination of absolute configuration and conformational preferences, but also supramolecular interactions may be monitored. In order to expand the applicability of chiroptical systems, the development of functional materials exhibiting intense chiroptical responses is essential. As a proof of principle, we previously constructed chiroptical interfaces via thioacetate-derivatized allenes. Because of the photoisomerization issues associated with allenes, we have recently proposed their replacement by spirobifluorenes to achieve robust chiroptical systems. Thus, we hereby present the design and synthesis of chiral spirobifluorenes bearing thioacetates suitable for suface functionalization.

Chiroptical responses have been an essential tool over the last decades for chemical structural elucidation due to their exceptional sensitivity to geometry and intermolecular interactions. In recent times, there has been an increasing interest in the search for more efficient sensing by the rational design of tailored chiroptical systems. In this review article, advances made in chiroptical systems towards their implementation in sensing applications are summarized. Strategies to generate chiroptical responses are illustrated. Theoretical approaches to assist in the design of these systems are discussed. The development of efficient chiroptical reporters in different states of matter, essential for the implementation in sensing devises, is reviewed. In the last part, remarkable examples of chiroptical sensing applications are highlighted.

Several theoretical studies have proposed strategies to reach helical molecular orbitals (Hel-MOs) in [n]cumulenes. While chiral even-[n] cumulenes feature Hel-MOs, odd-[n] cumulenes may also present them if the terminal groups lie on different planes. However, the hitherto proposed systems have been either experimentally unfeasible or resulted in opposite pseudo-degenerated Hel-MOs, impeding their use in real applicatons. To overcome this challenge, we hereby demonstrate the introduction of a remarkable energy difference between helical orbitals of opposite twist by fixing the torsion angle between the terminal groups in butadiyne fragments. In order to experimentally lock the conformation of the terminal groups, we designed cyclic architectures by combining acetylenes with chiral spirobifluorenes. A straightforward synthetic strategy along with the high stability allowed the isolation and full characterization of systems presenting distinct helical orbitals. Finally, a thorough computational analysis revealed that the most significant optical responses of these systems originate mainly from the exciton coupling between the featured diphenylbutadiyne fragments. This novel strategy opens now access to the development of systems with distinct helical molecular orbitals suitable for their implementation into chiroptical and optoelectronic applications.

The last decade has seen a huge growth in the construction of chiral systems to expand the scope of chiroptical applications. Dependence of chiroptical response on molecular conformation typically leads to low chiroptical intensities of chiral systems that feature several conformations in solution. In this respect, allenes were employed for the preparation of open and cyclic oligomers as well as molecular cages, presenting remarkable chiroptical responses in solution. Their molecular chirality was also transferred to metal surfaces, yet photoisomerization of allenes limited their further exploration. In search of a more robust chiral axis, theoretical and experimental studies confirmed that spirobifluorenes could give rise to stable systems with tailored optical and chiroptical properties. Additionally, incorporating a conformational lock into spirobifluorene cyclic architectures served as an efficient strategy towards the generation of distinct helical molecular orbitals. This review article outlines our results on developing device-compatible chiroptical systems through axially chiral allenes and spirobifluorenes. The contribution from other research groups is presented briefly.

Chiroptical responses have been an essential tool over the last decades for chemical 10 structural elucidation due to their exceptional sensitivity to geometry and intermolecular 11 interactions. In recent times, there has been an increasing interest for the search of more efficient 12 sensing by the rational design of tailored chiroptical systems. In this Review article, advances on 13 chiroptical systems towards their implementation in sensing applications are summarized. 14 Strategies to generate chiroptical responses are illustrated. Theoretical approaches to assist in the 15 design of these systems are discussed. Development of efficient chiroptical reporters in different 16 states of matter, essential for the implementation in sensing devises, is reviewed. In the last part, 17 remarkable examples of chiroptical sensing applications are highlighted. 18

Spirobifluorene derivatives find use in many end-user applications. Therefore, further expansion of their scope is the focus of many research studies. However, although the optical properties of spirobifluorenes can be greatly tuned through incorporation of metal complexes, to date, spirobifluorene metallaaromatics remain unknown. Taking advantage of the versatility of our methodology for the synthesis of metallaaromatic systems, this work reports the first metallaaromatic spirobifluorene compound. The presence of an Ir atom was found to redshift the absorption maximum by ca. 1.1 eV compared to bare spirobifluorene. Additionally, X-ray analysis as well as anisotropy of the current-induced density calculations revealed this compound to be of aromatic nature. The high stability in solution, solid state, under air, and at high temperature, as well as distinct optical properties of this new class of compounds are expected to open new frontiers for chiroptical and optoelectronic applications.

It is well established that chiroptical responses, based on the unique reaction to circularly polarized light by chiral non-racemic systems, are sensitive to the stereochemistry of the featuring systems. This behavior has promoted the use of chiroptical spectroscopies as a mandatory tool in the structure determination of molecules for decades. Recently, the higher sensitivity of chiroptical techniques compared to the conventional UV/Vis absorption and fluorescence spectroscopies or electrochemistry has awakened much interest in the development of chiroptical everyday applications. While chiroptical responses could be predicted by ab initio calculations, large systems calculated at a high level of theory may have an important computational cost; therefore, more intuitive methods are desired to design systems with tailored chiroptical responses. In this regard, the exciton chirality method has been often used in conformationally stable systems incorporating at least two independent chromophores. Taking this method into consideration, in our previous work, we described the chiroptical symmetry analysis (CSA) based on symmetry selection rules. To explore the scope of the CSA, herein we perform the chiroptical symmetry analysis of diverse trianglimines and draw general conclusions to assist on the design of chiroptical systems with high symmetry.

Chiroptical responses have been an essential tool over the last decades for chemical structural elucidation due to their exceptional sensitivity to geometry and intermolecular interactions. In recent times, there has been an increasing interest for the search of more efficient sensing by the rational design of tailored chiroptical systems. In this Review article, advances on chiroptical systems towards their implementation in sensing applications are summarized. Strategies to generate chiroptical responses are illustrated. Theoretical approaches to assist in the design of these systems are discussed. Development of efficient chiroptical reporters in different states of matter, essential for the implementation in sensing devises, is reviewed. In the last part, remarkable examples of chiroptical sensing applications are highlighted.

Chiroptical methods have been proven to be superior compared to their achiral counterparts for the structural elucidation of many compounds. To expand the use of chiroptical systems to everyday applications, the development of functional materials exhibiting intense chiroptical responses is essential. Particularly, tailored and robust interfaces compatible with standard device operation conditions are required. Herein, we present the design and synthesis of chiral allenes and their use for the functionalization of gold surfaces. The self-assembly results in a monolayer-thin room-temperature-stable upstanding chiral architecture as ascertained by ellipsometry, X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure. Moreover, these nanostructures anchored to device-compatible substrates feature intense chiroptical second harmonic generation. Both straightforward preparation of the device-compatible interfaces along with their chiroptical nature provide major prospects for everyday applications.