Choosing a Model and Appropriate Transition Dipole Moments for Time-Dependent Calculations of Intervalence Electronic Transitions

1996 ◽  
Vol 100 (21) ◽  
pp. 8712-8721 ◽  
Author(s):  
David S. Talaga ◽  
Jeffrey I. Zink
Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 524
Author(s):  
Austin Biaggne ◽  
William B. Knowlton ◽  
Bernard Yurke ◽  
Jeunghoon Lee ◽  
Lan Li

The aggregation ability and exciton dynamics of dyes are largely affected by properties of the dye monomers. To facilitate aggregation and improve excitonic function, dyes can be engineered with substituents to exhibit optimal key properties, such as hydrophobicity, static dipole moment differences, and transition dipole moments. To determine how electron donating (D) and electron withdrawing (W) substituents impact the solvation, static dipole moments, and transition dipole moments of the pentamethine indocyanine dye Cy5, density functional theory (DFT) and time-dependent (TD-) DFT calculations were performed. The inclusion of substituents had large effects on the solvation energy of Cy5, with pairs of withdrawing substituents (W-W pairs) exhibiting the most negative solvation energies, suggesting dyes with W-W pairs are more soluble than others. With respect to pristine Cy5, the transition dipole moment was relatively unaffected upon substitution while numerous W-W pairs and pairs of donating and withdrawing substituents (D-W pairs) enhanced the static dipole difference. The increase in static dipole difference was correlated with an increase in the magnitude of the sum of the Hammett constants of the substituents on the dye. The results of this study provide insight into how specific substituents affect Cy5 monomers and which pairs can be used to engineer dyes with desired properties.


1993 ◽  
Vol 71 (10) ◽  
pp. 1663-1671 ◽  
Author(s):  
Shahul H. Nilar ◽  
Ajit J. Thakkar ◽  
Anne E. Kondo ◽  
William J. Meath

The "giant dipole" molecules, NR1R2—C6H4—(C≡C)n—C6H4—NO2n = 0, 1, 2, are studied theoretically for three sets of substituents: R1 = R2 = H, R1 = H, R2 = CH3, and R1 = R2 = CH3. For each of these nine molecules, the energies, and permanent and transition dipole moments for the 20 lowest electronic states are calculated using the intermediate neglect of differential overlap (INDO) approximation at the configuration interaction with single excitations (CIS) level. Static polarizabilities and hyperpolarizabilities for the ground states are reported for these "push–pull" molecules. The changes in the physical properties of interest due to increase in conjugation length and the inductive effect of substituents on the donor group attached to the rings are discussed. The energies and permanent and transition dipole moments for the ten lowest electronic states are tabulated for use in future studies of the spectral and dynamical effects of permanent dipoie moments on laser-induced one- and multi-photon electronic transitions in realistic models for many-level giant dipole molecules.


RSC Advances ◽  
2020 ◽  
Vol 10 (70) ◽  
pp. 42897-42902
Author(s):  
Chan Hee Lee ◽  
Shin Hyung Choi ◽  
Sung Joon Oh ◽  
Jun Hyeon Lee ◽  
Jae Won Shim ◽  
...  

The linear D–A–D type of molecular structure of AcPYM and PxPYM enhances the horizontally oriented alignment and up to 87% of the horizontal transition dipole moments in the host matrix is realized.


2020 ◽  
Vol 117 (51) ◽  
pp. 32395-32401
Author(s):  
Jitka Myšková ◽  
Olga Rybakova ◽  
Jiří Brynda ◽  
Petro Khoroshyy ◽  
Alexey Bondar ◽  
...  

Fluorescent molecules are like antennas: The rate at which they absorb light depends on their orientation with respect to the incoming light wave, and the apparent intensity of their emission depends on their orientation with respect to the observer. However, the directions along which the most important fluorescent molecules in biology, fluorescent proteins (FPs), absorb and emit light are generally not known. Our optical and X-ray investigations of FP crystals have now allowed us to determine the molecular orientations of the excitation and emission transition dipole moments in the FPs mTurquoise2, eGFP, and mCherry, and the photoconvertible FP mEos4b. Our results will allow using FP directionality in studies of molecular and biological processes, but also in development of novel bioengineering and bioelectronics applications.


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