Thorough understanding the nonlinear optical properties of dipyrromethene/closo-dodecaborane/diketopyrrolopyrrole hybrid chromophores: module contribution, linear combination, one-/two-dimensional difference and carborane’s arrangement
In an attempt to enrich the understanding about essential structure-nonlinear optical (NLO) property correlations in multi-component photoactive boron dipyrromethene/closo-dodecaborane/diketopyrrolopyrrole (BOD/Cp/DPP) hybrid chromophores, three basic modules, three dyads, and five triads have been systematically designed and comparatively investigated. Herein, the geometric and electronic structures, electronic absorption spectra, polarizabilities (αave) and first hyperpolarizabilities (βtot) were carried out using density functional theory. It is found that the absorption spectrum and αave results of our current chromophores are highly modular, which can be efficiently deduced from corresponding building blocks. The βtot values are determined by the BOD module because of its dominant polarization mechanisms, rather than a general dependence on the molecular size/volume. Furthermore, we presented a comprehensive assessment of the evolution of structure and photophysical (NLO) properties upon linear combination of basic functional modules, one-/two-dimensional geometric difference and carborane’s different substituted position driving from the pristine rod-like BOD-Cp-DPP platform. The take home messages suggest that the quadratic NLO behaviors can be rationally tuned by the minor modifications in the structure. Overall, we believe that the proposed chromophores and even more the reasoning for their design/recognition will be helpful for the exploration of more efficient NLO materials than those currently available.