Thermally stable ferrocenyl “push–pull” chromophores with tailorable and switchable second-order non-linear optical response: synthesis and structure–property relationship

A theoretical investigation of one-dimensional lithium-bonded chain: enhanced first hyperpolarizability and little red-shift

“…3, it can be found that Lisalts have a more negative electrostatic potential on the nitrogen atoms, and have a more positive electrostatic potential on the lithium atom. Furthermore, comparing the electrostatic potentials between (NC-CC-Li) 8 and (NC-Li) 8 , we found that the electrostatic potential on the nitrogen atom is more negative in (NC-Li) 8 than in (NC-CC-Li) 8 , and that the electrostatic potential on the lithium atom is more positive in (NC-Li) 8 than in (NC-CC-Li) 8 . In (NC-CC-Li) 8 and (NC-Li) 8 , the positive electrostatic potentials on the lithium atoms become larger from the left to right; meanwhile, the negative electrostatic potentials on nitrogen atoms become larger from left to right.…”

“…(3) In the same structure, C n -Li n with the longest bond distance and Li n -N n+1 with the shortest bond distance are located in the middle of the one-dimensional structure. For example, in (NC-CC-Li) 8 , C n -Li n with the longest bond distance is C 4 -Li 4 and Li n -N n+1 with the shortest bond distance Li 4 -N 5 . (4) We found that changes in C-Li and Li-N distances in (NC-Li) n are similar to those in (NC-CC-Li) n .…”

“…The isodensity plots of (NC-CC-Li) 8 and (NC-Li) 8 are shown in Fig. 2 (those of other chains are provided in Fig.…”

“…5, the interesting relationship between β 0 and λ max suggests that (NC-CC-Li) n and (NC-Li) n have a unique advantage in moderating this apparent contradiction, that is, with increasing n, they can achieve large first hyperpolarizability with only a slight red-shift. For example, compared with other Li-bond systems, although the lithium salt of pyridazine Li-H 3 C 4 N 2 has a β 0 value of 859 a.u., which is larger than that of (NC-CC-Li) 8 (417 a.u. ), the λ max of Li-H 3 C 4 N 2 (257 nm) is larger than that of (NC-CC-Li) 8 (176 nm).…”

“…One-dimensional π-conjugated systems [1][2][3][4][5][6][7][8][9][10] have been investigated extensively in second-order nonlinear optical (NLO) materials design, because large molecular hyperpolarizability, β, can be obtained by optimizing donor/ acceptor moiety strengths and/or extending the π-conjugated path. However, there are some apparent drawbacks with onedimensional structural compounds.…”