Linear allenic linkage for nonlinear optics: A computational study of the role of mutually orthogonal π-orbitals in controlling the charge transfer, hyperpolarizability and absorption properties in some donor–acceptor substituted allenes

Abstract: First hyperpolarizability (β) of some donor–acceptor substituted allenes where, unlike in the earlier studies, the donor and acceptors are mutually orthogonal to each other are carried out using couple perturbed Hartree–Fock (CPHF) method at HF/6-31G level of theory. All the molecules show reasonably good β values. Configuration interaction singles (CIS) analysis shows that most of the molecules absorb in the UV-region and thus are transparent in the region of interest. On the other hand, zwitterionic allenes show unusually smaller β values. Analysis shows that, structural deformation in zwitterionic allenes leads to a through space (TS) charge transfer and ultimately reducing the β. But in zwitterionic allenes with resonance stabilized donors, enhancement in β can be achieved. It is suggested that with the absorption in the UV region, reasonably good values of β and the chirality due to asymmetric substitution, these molecules could be potential candidates for device applications. [Copyright &y& Elsevier]