Ca–Ca interaction in inverse sandwich Ca–C8H8–Ca

The inverse sandwich Ca–C8H8–Ca is predicted to be open-shell singlet Ca–C8H8–Ca. The singlet diradical character is caused by the C8H8 ligand preventing the spin-paired electrons of different calcium atoms from forming Ca–Ca bonds. A direct Ca–Ca bond is favorable in closed-shell singlet (DME)3Ca–C8H8–Ca(DME)3, because dimethyl ether molecules could push the spin-paired electrons of different calcium atoms to migrate towards the direction of Ca–Ca bonding.

Download Full-text

Evolution of the electronic structure in open-shell donor-acceptor organic semiconductors

Nature Communications ◽

10.1038/s41467-021-26173-3 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Zhongxin Chen ◽

Wenqiang Li ◽

Md Abdus Sabuj ◽

Yuan Li ◽

Weiya Zhu ◽

...

Keyword(s):

Electronic Structure ◽

Organic Semiconductors ◽

High Performance ◽

Closed Shell ◽

Open Shell ◽

Ground State Structure ◽

Structure Property ◽

System A ◽

Diradical Character ◽

Donor Acceptor

AbstractMost organic semiconductors have closed-shell electronic structures, however, studies have revealed open-shell character emanating from design paradigms such as narrowing the bandgap and controlling the quinoidal-aromatic resonance of the π-system. A fundamental challenge is understanding and identifying the molecular and electronic basis for the transition from a closed- to open-shell electronic structure and connecting the physicochemical properties with (opto)electronic functionality. Here, we report donor-acceptor organic semiconductors comprised of diketopyrrolopyrrole and naphthobisthiadiazole acceptors and various electron-rich donors commonly utilized in constructing high-performance organic semiconductors. Nuclear magnetic resonance, electron spin resonance, magnetic susceptibility measurements, single-crystal X-ray studies, and computational investigations connect the bandgap, π-extension, structural, and electronic features with the emergence of various degrees of diradical character. This work systematically demonstrates the widespread diradical character in the classical donor-acceptor organic semiconductors and provides distinctive insights into their ground state structure-property relationship.

Download Full-text

Anti-ohmic Nanoconductors: Myth, Reality and Promise

10.26434/chemrxiv-2021-bf1nx ◽

2021 ◽

Author(s):

Ashima Bajaj ◽

Md. Ehesan Ali

Keyword(s):

Symmetry Breaking ◽

Ground State ◽

Closed Shell ◽

Open Shell ◽

Molecular Junctions ◽

Spatial Symmetry ◽

New Family ◽

Diradical Character ◽

Classical Behavior

The recent accomplishments in the design of molecular nanowires characterised by an increasing conductance with length has embarked the origin of extraordinary new family of molecular junctions referred to as "anti-ohmic" wires. Herein, this highly desirable, non-classical behavior, has been examined for the longer enough molecules exhibiting pronounced diradical character in their ground state within the unrestricted DFT formalism with spin and spatial symmetry breaking. We demonstrate that highly conjugated acenes signals higher resistance in open-shell singlet (OSS) configuration as compared to their closed-shell counterparts. This anomaly has been further put to proof for experimentally certified cumulene wires, which reveals phenomenal modulation in the transport characteristics such that an increasing conductance is observed in closed-shell limit, while higher cumulenes in OSS ground state yields a regular decay of conductance.

Download Full-text

A BODIPY-Bridged Bisphenoxyl Diradicaloid: Solvent-Dependent Diradical Character and Physical Properties

Molecules ◽

10.3390/molecules24081446 ◽

2019 ◽

Vol 24 (8) ◽

pp. 1446 ◽

Cited By ~ 8

Author(s):

Fang Miao ◽

Hoa Phan ◽

Jishan Wu

Keyword(s):

Polar Solvent ◽

Closed Shell ◽

Dipole Interaction ◽

Open Shell ◽

Crystallographic Analysis ◽

Structural Flexibility ◽

Polar Solvents ◽

X Ray ◽

Diradical Character ◽

Paramagnetic Activity

We report a new boron dipyrromethene (BODIPY)-bridged bisphenoxyl diradicaloid (2), which showed closed-shell diamagnetic character in less polar solvents such as dichloromethane but open-shell diradical character with paramagnetic activity in the very polar solvent N,N-dimethylformamide. X-ray crystallographic analysis of 2 revealed an anti-parallel stacked dimer structure via intermolecular dipole–dipole interaction, and the observed solvent-dependent diradical character can be explained by the different dihedral angles between the phenoxyl units and the BODIPY bridge, and structural flexibility of the molecule in different solvents. Compound 2 also exhibited solvent-dependent optical and electrochemical properties.

Download Full-text

Transalkylierung und protonenkatalysierte C-C-Spaltung bei n-Butyl-und n-Pentylbenzol in der Gasphase / Transalkylation and Proton Catalyzed C-C-Cleavage of Gaseous n-Butyl and w-Pentyl Benzenes

Zeitschrift für Naturforschung B ◽

10.1515/znb-1979-0325 ◽

1979 ◽

Vol 34 (3) ◽

pp. 495-501 ◽

Cited By ~ 19

Author(s):

C. Wesdemiotis ◽

H. Schwarz ◽

C. C. Van de Sande ◽

F. Van Gaever

Keyword(s):

Hydrogen Exchange ◽

Closed Shell ◽

Open Shell ◽

Molecular Ions ◽

Exchange Reactions ◽

Intramolecular Exchange ◽

Carbon Carbon Bond ◽

Exchange Processes ◽

Reaction Channels ◽

Alkyl Benzenes

Abstract The investigation of several 13carbon and deuterium labelled n-butyl and n-pentyl benzenes demonstrate that chemical ionization (reagent gas: methane) induces specific carbon-carbon bond cleavages of the alkyl group. The extent of competing reaction channels as for instance direct alkene elimination versus dealkylation/reprotonation is analyzed. Partial hydrogen exchange processes between reagent ions and substrate molecules are restricted to the phenyl ring. Intramolecular exchange reactions between the side chain and the aromatic ring which are typical for the open shell molecular ions of alkyl benzenes are not observed for analogous closed shell cations.

Download Full-text

Exploring Cu/Al cluster growth and reactivity: from embryonic building blocks to intermetalloid, open-shell superatoms

Chemical Science ◽

10.1039/d1sc00268f ◽

2021 ◽

Author(s):

Max Schütz ◽

Christian Gemel ◽

Maximilian Muhr ◽

Christian Jandl ◽

Samia Kahlal ◽

...

Keyword(s):

Closed Shell ◽

Building Blocks ◽

Open Shell ◽

Cluster Growth ◽

Powerful Technique

Cu/Al cluster growth reactions leading to open- and closed-shell superatoms are investigated. Therein, LIFDI-MS is presented as a powerful technique for the in situ detection of cluster identities and reactivity patterns.

Download Full-text

Open-Shell and Closed-Shell Quinoid–Aromatic Conjugated Polymers: Unusual Spin Magnetic and High Charge Transport Properties

ACS Applied Materials & Interfaces ◽

10.1021/acsami.0c15893 ◽

2021 ◽

Author(s):

Yunseul Kim ◽

Yeon-Ju Kim ◽

Yeong-A Kim ◽

Eunhwan Jung ◽

Yoonjung Mok ◽

...

Keyword(s):

Conjugated Polymers ◽

Charge Transport ◽

Transport Properties ◽

Closed Shell ◽

Open Shell ◽

High Charge

Download Full-text

Non-classical S-Heteroacenes with o -Quinoidal Conjugation and Open-Shell Diradical Character

Chemistry - A European Journal ◽

10.1002/chem.201701813 ◽

2017 ◽

Vol 23 (35) ◽

pp. 8525-8531 ◽

Cited By ~ 11

Author(s):

Xueliang Shi ◽

Tullimilli Y. Gopalakrishna ◽

Qing Wang ◽

Chunyan Chi

Keyword(s):

Open Shell ◽

Diradical Character

Download Full-text

Stresses and Deformations of Toroidal Shells of Elliptical Cross Section: With Applications to the Problems of Bending of Curved Tubes and of the Bourdon Gage

Journal of Applied Mechanics ◽

10.1115/1.4010404 ◽

1952 ◽

Vol 19 (1) ◽

pp. 37-48

Author(s):

R. A. Clark ◽

T. I. Gilroy ◽

E. Reissner

Keyword(s):

Cross Section ◽

Cross Sections ◽

Practical Interest ◽

Closed Shell ◽

Open Shell ◽

Elliptical Cross Section ◽

Axially Symmetric ◽

Elliptical Cross ◽

Two Parameters ◽

Toroidal Shells

Abstract This paper is concerned with the application of the theory of thin shells to several problems for toroidal shells with elliptical cross section. These problems are as follows: (a) Closed shell subjected to uniform normal wall pressure. (b) Open shell subjected to end bending moments. (c) Combination of the results for the first and second problems in such a way as to obtain results for the stresses and deformations in Bourdon tubes. In all three problems the distribution of stresses is axially symmetric but only in the first problem are the displacements axially symmetric. The magnitude of stresses and deformations for given loads depends in all three problems on the magnitude of the two parameters bc/ah and b/c where b and c are the semiaxes of the elliptical section, a is the distance of the center of the section from the axis of revolution, and h is the thickness of the wall of the shell. For sufficiently small values of bc/ah trigonometric series solutions are obtained. For sufficiently large values of bc/ah asymptotic solutions are obtained. Numerical results are given for various quantities of practical interest as a function of bc/ah for the values 2, 1, 1/2, 1/4 of the semiaxes ratio b/c. It is suggested that the analysis be extended to still smaller values of b/c and to cross sections other than elliptical.

Download Full-text