Heterocyclic Betaines Exhibiting Extremely Large First Hyperpolarizability: Ab Initio and INDO/S Calculations

The Origin of Coloration in Aromatic Polyimides. An Approach from Quantum Chemistry.

“…[13] The dark-gray regions correspond to those increased electron density in the excited state, while the light-gray regions correspond to depleted regions from the ground state. Both from the MOs and the charge difference map, it is found that the benzene ring derived from DDE acts as an electrondonating group and the five-membered imide and the benzene rings derived from PMDA act as electron withdrawing groups [14], and that the first excited state is characterized by a strong intramolecular CT. [12] For the M(A-D-A) model, I ~e ADA/ of the first excited Mate (387nm light absorption) was also calculated, and it is expressed as The CI coefficients show that the predominant elctronic transition is HOMO -a LUMO and that its contribution in the first excited state is estimated to be 49%. Based on the calculation of the MOs and the difference electron density between the ground and the first excited states (Figures 4(a), 4(b), and 4(c)) , the first excited state is found to be caused by an intramolecular CT similarly to the M(D-A-D) model.…”

Investigation of NLO properties of substituted (M)‐tetrathia‐[7]‐helicenes by semiempirical and DFT methods

“…A number of research groups have been active in the field of NLO materials based on organic molecules and several highly active materials have already been identified [1]. A typical class of such materials consists of molecular aromatic systems in which massive nonlinearities may be achieved with appropriate donor (D) and acceptor (A) substitution on the aromatic part of the molecule.…”

“…The semiempirical INDO/S (intermediate neglect of differential overlap approximation) methods have been widely use by Abe et al [1,9,10] to compute first-order hyperpolarizabilities based on the sum-over-states (SOS) method (in particular second harmonic generation) of acceptor-donor molecules, for example, 4-nitroaniline, 4-(dimethylamino)-4Ј-nitrostilbene, and heterocyclic pyridinium betain. They have shown good agreement between their own experimental values and their semiempirical results as well as with the values obtained from the ab initio molecular orbital (MO) method through the CPHF (coupled-perturbed Hartree-Fock) formalism.…”

Novel Synthesis of Hydrophilic Dipolar Chromophores using Dendronized Sulfonates

“…Stilbene-derived dipolar chromophores such as DANS has been reported to exhibit intense π-π* transition and typical negative solvatochromism (hypsochromic shift) in protic solvents. 18 Maximum band at 430 nm of molecule 9 in methanol shifted to 420 nm in water as shown in Figure 2. On the other hand, azo benzene-derived dipolar chromophore such as disperse red (DR) shows typical positive solvatochromism (bathochromic shift) caused by stabilized π* orbital.…”