Advanced organic nonlinear optical (NLO) materials have attracted increasing attention due to their multitude of applications in modern telecommunication devices. Arguably the most important advantage of organic NLO materials, relative to traditionally used inorganic NLO materials, is their short optical response time. Geminal amido esters with their donor-π-acceptor (D-π-A) architecture exhibit high levels of electron delocalization and substantial intramolecular charge transfer, which should endow these materials with short optical response times and large molecular (hyper)polarizabilities. In order to test this hypothesis, the linear and second-order nonlinear optical properties of five geminal amido esters, (E)-ethyl 3-(X-phenylamino)-2-(Y-phenylcarbamoyl)acrylate (1, X = 4-H, Y = 4-H; 2, X = 4-CH3, Y = 4-CH3; 3, X = 4-NO2, Y = 2,5-OCH3; 4, X = 2-Cl, Y = 2-Cl; 5, X = 4-Cl, Y = 4-Cl) were synthesized and characterized, whereby NLO structure-function relationships were established including intramolecular charge transfer characteristics, crystal field effects, and molecular first hyperpolarizabilities (β). Given the typically large errors (10-30%) associated with the determination of β coefficients, three independent methods were used: (i) density functional theory, (ii) hyper-Rayleigh scattering, and (iii) high-resolution X-ray diffraction data analysis based on multipolar modeling of electron densities at each atom. These three methods delivered consistent values of β, and based on these results, 3 should hold the most promise for NLO applications. The correlation between the molecular structure of these geminal amido esters and their linear and nonlinear optical properties thus provide molecular design guidelines for organic NLO materials; this leads to the ultimate goal of generating bespoke organic molecules to suit a given NLO device application.
Journal of Physical Chemistry C
J.M.C. thanks the 1851 Royal Commission of the Great Exhibition for a Design Fellowship, hosted by Argonne National Laboratory where work done was supported by the DOE Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. T.-C.L acknowledges the Taiwanese Government for a Studying Abroad Scholarship. C.M.A is indebted to the EPSRC UK for a DTA Ph.D. studentship (Grants EP/J500380/1 and EP/L504920/1). Y.T. is grateful for a Cavendish-NUDT Scholarship. The Swiss-Norwegian Collaborative Research Group at the ESRF, Grenoble, France, is thanked for access to synchrotron facilities. The OPAL reactor, ANSTO, Australia, is acknowledged for access to neutron scattering facilities via a program proposal, ID 1236. J.P-M. is grateful to Skidmore College for supporting this work via a full-year sabbatical with enhancement. All authors thank the EPSRC UK National Service for Computational Chemistry Software (NSCCS) and acknowledge contributions from its staff in supporting this work.
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Cole J, Lin T, Ashcroft C, et al. Relating the structure of geminal Amido Esters to their molecular hyperpolarizability. Journal of Physical Chemistry C. 2016;120(51):29439-29448. doi:10.1021/acs.jpcc.6b10724
Cole, J., Lin, T., Ashcroft, C., Pérez Moreno, J., Tan, Y., Venkatesan, P., … Ilangovan, A. (2016). Relating the structure of geminal Amido Esters to their molecular hyperpolarizability. Journal of Physical Chemistry C. American Chemical Society. https://doi.org/10.1021/acs.jpcc.6b10724
Cole, Jaqueline, Tzechia Lin, Christopher Ashcroft, Javier Pérez Moreno, Yizhou Tan, Perumal Venkatesan, Andrew P Higginbotham, et al. “Relating the Structure of Geminal Amido Esters to Their Molecular Hyperpolarizability.” Journal of Physical Chemistry C. American Chemical Society, 2016. https://doi.org/10.1021/acs.jpcc.6b10724.
J. Cole et al., “Relating the structure of geminal Amido Esters to their molecular hyperpolarizability,” Journal of Physical Chemistry C, vol. 120, no. 51. American Chemical Society, pp. 29439–29448, 2016.
Cole J, Lin T, Ashcroft C, Pérez Moreno J, Tan Y, Venkatesan P, Higginbotham AP, Pattison P, Edwards A, Piltz R, Clays K, Ilangovan A. 2016. Relating the structure of geminal Amido Esters to their molecular hyperpolarizability. Journal of Physical Chemistry C. 120(51), 29439–29448.
Cole, Jaqueline, et al. “Relating the Structure of Geminal Amido Esters to Their Molecular Hyperpolarizability.” Journal of Physical Chemistry C, vol. 120, no. 51, American Chemical Society, 2016, pp. 29439–48, doi:10.1021/acs.jpcc.6b10724.