Existence of ring currents in cyclic conjugated molecules and their contribution to the diamagnetic susceptibility

1971 ◽  
Vol 12 (3) ◽  
pp. 507-508 ◽  
Author(s):  
M. D. Kumanova ◽  
T. K. Rebane
Keyword(s):  
Diamagnetic Susceptibility ◽  
Conjugated Molecules ◽  
Ring Currents

Patterns of Ring Currents in Conjugated Molecules:  A Few-Electron Model Based on Orbital Contributions

2001 ◽  
Vol 105 (41) ◽  
pp. 9553-9562 ◽  
Author(s):  
E. Steiner ◽  
P. W. Fowler
Keyword(s):  
Electron Model ◽  
Conjugated Molecules ◽  
Model Based ◽  
Ring Currents

The anisotropy of the g -factor for polycyclic hydrocarbons

1964 ◽  
Vol 278 (1372) ◽  
pp. 129-136 ◽  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Chemical Shift ◽  
Diamagnetic Susceptibility ◽  
Paramagnetic Species ◽  
Polycyclic Hydrocarbon ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Ring Currents ◽  
Self Consistent

An external magnetic field acting on a polycyclic hydrocarbon induces ring currents of mobile electrons in its various rings. This effect can be observed in a diamagnetic molecule by means of the large anisotropies of diamagnetic susceptibility and chemical shift which are produced. For paramagnetic species these observations are no longer available and it is suggested that the anisotropy of the electronic g -factor should be used instead. This arises because the secondary magnetic field of the ring currents helps to orient the electron spins. In the Hamiltonian it is the spin-other-orbit term which produces this interaction. The magnitude of this term is calculated for various species using the unrestricted molecular orbital theory in its self-consistent form and A g zz is of the order 3 x 10 -5.

Visualization and Manipulation of Molecular Motion in Solid State through Photo-Induced Clusteroluminescence

2019 ◽  
Author(s):  
Haoke Zhang ◽  
Lili Du ◽  
Lin Wang ◽  
Junkai Liu ◽  
Qing Wan ◽  
...  
Keyword(s):  
Quantum Mechanics ◽  
Excited State ◽  
Solid State ◽  
Light Source ◽  
Molecular Motion ◽  
Molecular Machine ◽  
Conjugated Molecules ◽  
Time Resolved ◽  
Packing Structure ◽  
New Strategy

<p>Building molecular machine has long been a dream of scientists as it is expected to revolutionize many aspects of technology and medicine. Implementing the solid-state molecular motion is the prerequisite for a practical molecular machine. However, few works on solid-state molecular motion have been reported and it is almost impossible to “see” the motion even if it happens. Here the light-driven molecular motion in solid state is discovered in two non-conjugated molecules <i>s</i>-DPE and <i>s</i>-DPE-TM, resulting in the formation of excited-state though-space complex (ESTSC). Meanwhile, the newly formed ESTSC generates an abnormal visible emission which is termed as clusteroluminescence. Notably, the original packing structure can recover from ESTSC when the light source is removed. These processes have been confirmed by time-resolved spectroscopy and quantum mechanics calculation. This work provides a new strategy to manipulate and “see” solid-state molecular motion and gains new insights into the mechanistic picture of clusteroluminescence.<br></p>

Ab initio Hartree-Fock Investigation of π-Conjugated Compounds Presenting Large βv/βe Ratio: Merocyanines

1998 ◽  
Vol 63 (9) ◽  
pp. 1295-1308 ◽  
Author(s):  
Benoît Champagne ◽  
Thierry Legrand ◽  
Eric A. Perpete ◽  
Olivier Quinet ◽  
Jean-Marie André
Keyword(s):  
Ab Initio ◽  
First Hyperpolarizability ◽  
Conjugated Molecules ◽  
Hartree Fock ◽  
Experimental Discovery ◽  
Conjugated Compounds ◽  
Molecular Frame

CHF/6-311G* calculations of the first electronic and vibrational hyperpolarizabilities reveal that merocyanines present a substantial βv/βe ratio under their quinonoid nonpolar form. It originates from a large vibrational first hyperpolarizability whereas its electronic counterpart is small for this class of push-pull π-conjugated molecules. The transition from the quinonoid to the aromatic configuration is accompanied by an increase of βe and a decrease of the βv/βe ratio as well as by a ≈ 180° rotation in the plane of the molecule of βe and βv with respect to the molecular frame. Our results support the recent experimental discovery that antiparallel aggregation of aromatic and quinonoid forms of merocyanine is energetically favoured and that their first hyperpolarizabilities, which combine constructively, present both electronic and non purely electronic origins.

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