Physical Chemistry Chemical Physics

doi: 10.1039/d3cp90222fpmid: N/A

doi: 10.1039/d3cp90223dpmid: N/A

doi: 10.1039/d3cp90224bpmid: N/A

Kozáková, Silvia; Alharzali, Nissrin; Černušák, Ivan

doi: 10.1039/d3cp03887dpmid: 37901943

All-carbon atomic rings, cyclo[n]carbons, have recently attracted vivid attention of experimentalists and theoreticians. Among them, cyclo[18]carbon is the most studied system. In this paper, we summarize and review various properties of cyclo[n]carbons, emphasising the aspects of their aromaticity/antiaromaticity. In the first part, the trends in bonding patterns and selected aromaticity indices with the increasing size of the rings are discussed. In the second part we explore the properties of catenane models based on interlocked cyclo[18]carbon rings from different perspectives and investigate their behaviour under the action of external force using computational experiments.

Merten, Christian

doi: 10.1039/d3cp03408apmid: 37881890

Vibrational circular dichroism (VCD) spectroscopy has become an important part of the (stereo-)chemists’ toolbox as a reliable method for the determination of absolute configurations. Being the chiroptical version of infrared spectroscopy, it has also been recognized as being very sensitive to conformational changes and intermolecular interactions. This sensitivity originates from the fact that the VCD spectra of individual conformers are often more different than their IR spectra, so that changes in conformational distributions or band positions and intensities become more pronounced. What is an advantage for studies focussing on intermolecular interactions can, however, quickly turn into a major obstacle during AC determinations: solute–solvent interactions can have a strong influence on spectral signatures and they must be accurately treated when simulating VCD and IR spectra. In this perspective, we showcase selected examples which exhibit particularly pronounced solvent effects. It is demonstrated that it is typically sufficient to model solute–solvent interactions by placing single solvent molecules near hydrogen bonding sites of the solute and subsequently use the optimized structures for spectra simulations. This micro-solvation approach works reasonably well for medium-sized, not too conformationally flexible molecules. We thus also discuss its limitations and outline the next steps that method development needs to take in order to further improve the workflows for VCD spectra predictions.

Mohammadi, Khatereh; Bentria, El Tayeb; Bonakala, Satayanaraya; Medina, Johanne; Ayeche, Lamis; Fadlallah, Joelle; El Mellouhi, Fedwa

doi: 10.1039/d3cp02435kpmid: 37906034

Color blindness affects 5% of the world's population, and it can challenge the accessibility and inclusivity of science, technology, engineering and mathematics (STEM) education. Inspired by the fourth United Nations’ (UN) sustainable development goal of quality education, we aim to provide sustainable and accessible resources for lifelong learning for all. In this work, we present MatAR, an educational augmented reality (AR) mobile app that enables colorblind learners to visualize 3D molecular structures by color pallet optimization. Leveraging Vuforia's cloud database, MatAR offers a sustainable solution for storing and accessing target images. Accessibility to AR applications for physics, chemistry, and materials science learning is currently limited. We believe that MatAR provides immersive visualization solutions for education and academic/industry research and has the potential to enhance the accessibility of STEM education for learners with color vision deficiencies and promote inclusive and equitable quality education, aligning with the united nations sustainable development goals.

Tada, Kohei; Kawakami, Takashi; Hinuma, Yoyo

doi: 10.1039/d3cp02988cpmid: 37795574

The analysis of the diradical state of functional open-shell molecules is important for understanding their physical properties and chemical reactivity. The diradical character is an important factor in the functional elucidation and design of open-shell molecules. In recent years, attempts have been made to immobilise functional open-shell molecules on surfaces to form devices. However, the influence of surface interactions on the diradical state remains unclear. In this study, the physisorption structures of p-benzyne, which is a typical diradical molecule, on MgO(001) and SrO(001) surfaces are used as models to investigate how the diradical character is affected by physisorption. This is done using approximate spin-projected density functional theory calculations with dispersion correction and plane-wave basis (AP-DFT-D3/plane-wave calculations). The diradical character change (Δy) due to adsorption can be categorised into three factors, namely the change due to the distortion of the diradical molecule (Δydis), the interaction between neighbouring diradical molecules (Δycoh), and molecule-surface interactions (Δysurf). In all the calculated models, physisorption reduced the diradical character (Δy < 0), and the contribution of Δysurf was the largest among the three factors. The calculated results show that adsorption induces electron delocalisation to π-conjugated orbitals and intramolecular charge polarisation, both of which contribute to reducing the occupancy of singly occupied molecular orbitals. This indicates that the diradical character of p-benzyne is reduced by the stabilisation of the resonance structures. Furthermore, geometry optimisation of the surfaces shows that the chemical-soft surface (SrO) varies the diradical character more significantly than the chemical-hard surface (MgO). This study shows that the open-shell electronic state and stack structure of diradical molecules can be controlled through the analysis of the surface diradical state.

Zhu, Jiaduo; Su, Kai; Ren, Zeyang; Li, Yao; Zhang, Jinfeng; Zhang, Jincheng; Guo, Lixin; Hao, Yue

doi: 10.1039/d3cp03702apmid: 37846752

The extremely difficult ambipolar doping activation greatly hinders the outstanding performance of diamond for electronic devices. The main concern has been devoted to surface conduction by two-dimensional (2D) carriers. 2D hole gas (2DHG) in the diamond is induced by surface transfer doping dominated by the adsorbate's status and faces stability issues. Meanwhile, a feasible way to generate the other essential ambipolar carrier—2D electron gas (2DEG) is still lacking. We propose that the well-lattice-matched diamond/cBN(111) interfaces can spontaneously induce 2D ambipolar carriers with a giant density of 4.17 × 1014 cm−2, an order higher than other competitors. 2DEG and 2DHG can be separately achieved near the hetero-interfaces consisting of C–N and C–B bonds, respectively. Interestingly, the robust 2D charges are derived from a novel bulk-induced polarization-discontinuity at the interfaces, which can be attributed to an unexpected non-zero formal polarization of centrosymmetric cBN along the [111] direction. The existence of 2D ambipolar carriers at the diamond/cBN(111) interfaces has resolved the missing n-type conduction in diamond, thus opening up possibilities for complementary logic applications. Additionally, the high density of quantum-confined 2D ambipolar carriers provides an excellent platform for strongly correlated systems, which could lead to novel quantum information processing applications.

Black, E.; Kratzer, P.; Morbec, J. M.

doi: 10.1039/d3cp01895dpmid: 37721397

Using first-principles calculations based on density-functional theory, we investigated the adsorption of pentacene molecules on monolayer two-dimensional transition metal dichalcogenides (TMD). We considered the four most popular TMDs, namely, MoS2, MoSe2, WS2 and WSe2, and we examined the structural and electronic properties of pentacene/TMD systems. We discuss how monolayer pentacene interacts with the TMDs, and how this interaction affects the charge transfer and work function of the heterostructure. We also analyse the type of band alignment formed in the heterostructure and how it is affected by molecule–molecule and molecule–substrate interactions. Such analysis is valuable since pentacene/TMD heterostructures are considered to be promising for application in flexible, thin and lightweight photovoltaics and photodetectors.

Wu, Yibing; Xiao, Shu; Guo, Kaiwen; Qiao, Xianfeng; Yang, Dezhi; Dai, Yanfeng; Sun, Qian; Chen, Jiangshan; Ma, Dongge

doi: 10.1039/d3cp03437bpmid: 37882197

The lifetime of blue organic light-emitting diodes (OLEDs) has always been a big challenge in practical applications. Blue OLEDs based on triplet–triplet annihilation (TTA) up-conversion materials have potential to achieve long lifetimes due to fusing two triplet excitons to one radiative singlet exciton, but there is a lack of an in-depth understanding of exciton dynamics on degradation mechanisms. In this work, we established a numerical model of exciton dynamics to study the impact factors in the stability of doped blue OLEDs based on TTA up-conversion hosts. By performing transient electroluminescence experiments, the intrinsic parameters related to the TTA up-conversion process of aging devices were determined. By combining the change of excess charge density in the emitting layer (EML) with aging time, it is concluded that the TTA materials are damaged by the excess electrons in the EML during ageing, which is the main degradation mechanism of OLEDs. This work provides a theoretical basis for preparing long-lifetime blue fluorescent OLEDs.