Article
Chemistry, Physical
Atif Mahmood, Maria Dimitrova, Lukas N. Wirz, Dage Sundholm
Summary: The molecular structures of porphyrinoid cages were obtained by constructing small polyhedral graphs and optimizing them at the density functional theory level. Different structures were created by replacing vertices and edges with different units or bridges. Current-density calculations were performed to determine the aromatic character and pathways. The results showed that some structures had aromatic ring currents. The aromaticity of the structures changed upon oxidation.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Physical
Atif Mahmood, Maria Dimitrova, Lukas N. Wirz, Dage Sundholm
Summary: This study investigates the magnetically induced current densities (MICDs) of Zn-porphyrinoid nanostructures using density functional theory. The results show that these nanostructures are globally nonaromatic but can sustain ring currents locally.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Physics, Applied
Victor I. Kleshch, Vitali Porshyn, Pavel Serbun, Anton S. Orekhov, Rinat R. Ismagilov, Dirk Luetzenkirchen-Hecht, Alexander N. Obraztsov
Summary: Surface graphitization of needlelike diamond nanotips can be achieved by Joule heating, resulting in well-ordered graphene layers and better emission currents, making them promising for various applications.
APPLIED PHYSICS LETTERS
(2022)
Article
Nanoscience & Nanotechnology
Gongdong Wang, Mingyang Zheng, Zhendong Liu, Meng Wang
Summary: A flexible piezoresistive sensor with high anisotropy has been developed using internal vertically aligned carbon nanotubes and an external microdome structure. The sensor exhibits increased sensitivity in the pressure direction due to the synergistic effect of the carbon nanotubes and microdome structure. It has potential applications in areas such as human health monitoring, wearable electronics, and intelligent human-computer interaction.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Yongde Long, Jinguo Lin, Fenghui Ye, Wei Liu, Dan Wang, Qingqing Cheng, Rajib Paul, Daojian Cheng, Baoguang Mao, Riqing Yan, Linjie Zhao, Dong Liu, Feng Liu, Chuangang Hu
Summary: By proposing a possible cleavage mechanism, the study demonstrates that abundant carbon nanotube tips can be formed and easily modified with heteroatoms, enabling precise modulation of the atomic environment at the tips. CNTs with N,S-rich tips show a wide potential window and high selectivity for H2O2.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Physical
Mesias Orozco-Ic, Maria Dimitrova, Jorge Barroso, Dage Sundholm, Gabriel Merino
Summary: The pseudo-pi model is used to calculate the current densities and induced magnetic fields of large planar and nonplanar molecules, providing a way to assess the aromatic character of large carbon molecules by determining the pi-component of the ring-current strengths.
JOURNAL OF PHYSICAL CHEMISTRY A
(2021)
Article
Chemistry, Physical
Francesco F. Summa, Guglielmo Monaco, Paolo Lazzeretti, Riccardo Zanasi
Summary: This article focuses on the theoretical study of the interaction between molecules and optical fields through the integration of density functions. The study reveals the presence of density functions with origin invariance, which can be integrated to obtain electric dipole polarizability and optical rotatory power. The research also confirms the ubiquitous presence of counter-polarization regions near atomic nuclei and shows the existence of toroidal electron currents induced by time derivative of the electric field. The specific rotation power densities of the carbonyl chromophore are highlighted, demonstrating its asymmetry and causing optical rotation.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
J. F. Gloy, A. Siemens, P. Schmelcher
Summary: In this paper, we study a model system consisting of a particle moving along a toroidal helix and being influenced by a static potential and a harmonically oscillating electric field. It is found that in the limit of a small helix radius, the equations of motion coincide with those of the well-known Kapitza pendulum, indicating that the driven toroidal helix represents a generalization of the Kapitza pendulum. The stability of the two dominant fixed points in the Kapitza pendulum is also analyzed for a finite helix radius.
Article
Chemistry, Physical
Slavko Radenkovic, Sladana Dordevic
Summary: The effect of benzo-annelations on the magnetically induced current density was investigated using the CTOCD-DZ method and the PFI method. It was found that benzo-annelation in different positions relative to the central rings of anthracene and acridine derivatives has opposite effects on the intensity of n-electron currents.
CHEMICAL PHYSICS LETTERS
(2023)
Article
Chemistry, Physical
Qian Wang, Mesias Orozco-Ic, Dage Sundholm
Summary: The magnetically induced current-density susceptibility (MICD) and induced magnetic field around the [12]infinitene dianion have been calculated using density functional theory. The MICD is dominated by diatropic contribution, contradicting the belief that it is antiaromatic. The [12]infinitene dianion exhibits multiple through-space MICD pathways and weak local paratropic current-density contributions.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
T. Barberis, F. Porcelli, A. Yolbarsop
Summary: This article presents a new type of fast particle instability involving axisymmetric modes in magnetic fusion tokamak plasmas. The relevant dispersion relation consists of three roots, and the resonant interaction with fast ions can drive the oscillatory roots unstable.
Article
Chemistry, Multidisciplinary
Xiaobo He, Yanling Zhao, Yuanchu Dong, Fengxiang Yin, Xin Lin, Ruilong Ma, Jiaqi Li
Summary: Co3ZnC efficiently enhances the activity of Co@N, O co-doped carbons for hydrogen evolution. The presence of moderate Co3ZnC contributes to achieving an appropriate weighted Co 3d band centre, enhancing charger transfer, and optimizing the electrochemical active surface area. Thus, a low overpotential of around 219 mV can drive a high current density of 1000 mA cm(-2) under favorable conditions of moderate Co3ZnC.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Shuai Tang, Yu Zhang, Peng Zhao, Runze Zhan, Jun Chen, Shaozhi Deng
Summary: The study focused on enhancing the heat dissipation of few-layer graphene (FLG) by introducing a graphite interlayer between FLG and a tungsten substrate. This approach effectively reduced the temperature and the risk of vacuum breakdown, resulting in improved high-current field emission characteristics of single FLG samples.
Article
Chemistry, Physical
Yujie Hu, Changjun Zou
Summary: A magnetic material based on carbon nanotubes (CB[7]@Fe3O4/MWCNT -NH2) was fabricated for the effective removal of Pb (II) in water. The material showed excellent adsorption capabilities with a maximum adsorption capacity of 245.6 mg g(-1) at 20 degrees C. The adsorption process followed the Langmuir isotherm model and pseudo-second-order kinetic model.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2023)
Article
Chemistry, Multidisciplinary
Vivian Wang, Yingbo Zhao, Ali Javey
Summary: The use of alternating current voltage in electroluminescent devices with carbon nanotube contacts allows for efficient electroluminescence from various molecular materials. By optimizing device geometry, driving parameters, and material characteristics, the performance of these devices can be enhanced and limitations of conventional direct current schemes can be overcome. These AC-driven electroluminescent devices show promise in achieving internally efficient electroluminescence with different material thicknesses and energy barrier heights.
ADVANCED MATERIALS
(2021)
Article
Chemistry, Physical
Raphael J. F. Berger, Maria Dimitrova, Rinat T. Nasibullin, Rashid R. Valiev, Dage Sundholm
Summary: Magnetically induced ring currents are calculated using the Ampere-Maxwell law, and the feasibility of the method is demonstrated by integrating the shielding tensor components along the symmetry axis of highly symmetric molecules. The method can be used in combination with electronic structure codes capable of calculating NMR shielding tensors, and nucleus independent chemical shifts are related to the spatial derivative of the global ring-current strength along the z axis.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Rashid R. Valiev, Theo Kurten, Lenara Valiulina, Sergey Yu Ketkov, Viktor N. Cherepanov, Maria Dimitrova, Dage Sundholm
Summary: The current-density susceptibility tensor (CDT) of the lowest singlet and triplet states of metallocenothiaporphyrins with various metals has been studied, showing that most molecules follow the rules of aromaticity. Additionally, a unified extended aromaticity orbital-count rule has been proposed for molecules with odd and even numbers of occupied conjugated valence orbitals.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Ines Soldevilla, Aimara Garcia-Camacho, Rinat T. Nasibullin, M. Elena Olmos, Miguel Monge, Dage Sundholm, Rashid R. Valiev, Jose M. Lopez-de-Luzuriaga, Maria Rodriguez-Castillo
Summary: New three-coordinated gold(I) complexes with perhalophenyl groups were synthesized using a chelate ligand and [AuR(tht)] (R = C6F5, o-C6BrF4, p-C6BrF4, o-C6F4I, p-C6F4I). The crystal structures of two complexes showed distorted three-coordinated Au(I) complexes with different Au-P distances at the same gold atom. The complexes exhibited intense photoluminescence in the solid state at room temperature and at 77 K, and the study of their emission lifetime suggested the presence of thermally activated delayed fluorescence (TADF) processes at room temperature. The rate constants for intersystem crossing and reverse intersystem crossing of the photophysical processes were successfully computed through first-principle calculations, which supported the experimental observations with good agreement.
JOURNAL OF MATERIALS CHEMISTRY C
(2022)
Article
Chemistry, Physical
Atif Mahmood, Maria Dimitrova, Lukas N. Wirz, Dage Sundholm
Summary: The molecular structures of porphyrinoid cages were obtained by constructing small polyhedral graphs and optimizing them at the density functional theory level. Different structures were created by replacing vertices and edges with different units or bridges. Current-density calculations were performed to determine the aromatic character and pathways. The results showed that some structures had aromatic ring currents. The aromaticity of the structures changed upon oxidation.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Biochemistry & Molecular Biology
Li-Xia Bai, Mesias Orozco-Ic, Ximena Zarate, Dage Sundholm, Sudip Pan, Jin-Chang Guo, Gabriel Merino
Summary: This study systematically explores the potential energy surface of the B3Al4+ combination and finds a structure with fluxionality. The experimental results show that this structure exhibits both the dynamical behavior of a Reuleaux molecular triangle and the aromatic property.
Article
Chemistry, Physical
Hassan Rabaa, Andriy Grafov, Dage Sundholm
Summary: This study models the interactions between antimony-oxide clusters and trypanothione to understand their inhibitory activity against leishmaniasis. It is found that antimony-oxide clusters with at least one Sb-III atom can destroy the S-S bond of trypanothione, which is essential for the parasite's metabolism.
INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY
(2023)
Article
Chemistry, Organic
Akito Nakai, Qian Wang, Dage Sundholm, Takayuki Tanaka, Atsuhiro Osuka
Summary: A directly-linked Ni-II porphyrin-Ni-II pyricorrole hybrid was obtained by complexation of a internally-bridged octaphyrin(1.1.1.1.1.1.1.1) with a nickel ion. The structure was determined by X-ray diffraction analysis. The position of the pyridine moiety in the pyricorrole skeleton is different from previous reports. DFT calculations indicate that the thermodynamic stability of the Ni-II pyricorrole skeleton may drive this rearrangement.
ASIAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Atif Mahmood, Maria Dimitrova, Dage Sundholm
Summary: Two porphyrinoid nanorings were computationally studied by linking 40 Zn-porphyrin units with butadiyne bridges. The structural optimization of the molecules belonging to the D (40h) point group was performed using the Turbomole program at the DFT level. The aromatic character was studied by calculating the magnetically induced current-density susceptibility using the GIMIC program.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Physical
Mesias Orozco-Ic, Dage Sundholm
Summary: We have investigated the changes in aromaticity of two cyclobutadiene molecules as they approach the cubane structure. Our analysis based on magnetically induced current density and induced magnetic field calculations shows a transition from a strongly antiaromatic character to an aromatic state when the internuclear distance is decreased and the two C4H4 rings stack together, approaching the antiaromaticity of cubane.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Qian Wang, Jaakko Pyykko, Maria Dimitrova, Stefan Taubert, Dage Sundholm
Summary: In this study, the current density induced by an external magnetic field in a set of figure-eight-shaped expanded porphyrinoids was calculated using the Runge-Kutta method. The current density was divided into diatropic and paratropic contributions and analyzed separately. The results showed that the studied molecules had complex current density pathways with branching points. The N6 molecule had the strongest diatropic current-density flux of 13.2 nA T-1.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Optics
Maria Dimitrova, Dongming Jia, Joern Manz, Dage Sundholm
Summary: The magnetically induced electronic current density (MIC) in toluene is studied using density-functional theory. The findings show that the MIC near the methyl group is mainly diatropic, while the phenyl group ring is dominated by a paratropic MIC. The strength of the MIC near the methyl group is comparable to the ring current of benzene in a perpendicular magnetic field.
Article
Optics
Dongming Jia, Maria Dimitrova, Yuan Man, Dage Sundholm, Yonggang Yang
Summary: The theory of nuclear ring currents induced by external magnetic fields in torsional molecules is developed and applied to toluene. The study reveals that toluene exhibits mainly diatropic contributions to the nuclear ring current, with a very small paratropic contribution.
Article
Optics
K. Nordlund, M. Hori, D. Sundholm
Summary: We simulated the deceleration and transmission of antiprotons with keV-scale kinetic energies through polymer foils, and found that the coatings of materials on the surfaces have an impact on the transmission of antiprotons.
Article
Chemistry, Physical
Mesias Orozco-Ic, Nickolas D. Charistos, Alvaro Munoz-Castro, Rafael Islas, Dage Sundholm, Gabriel Merino
Summary: This study shows that the use of natural localized molecular orbitals (NLMOs) in the analysis of nuclear magnetic shielding tensors can lead to anomalous core contributions, which may significantly affect the interpretation of magnetic response and assessment of aromatic character in nonplanar molecules. By computing the induced magnetic field and current density, the core and sigma contributions to the magnetic response are determined, showing that the core contribution is small and localized at the nuclei.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)