Abstract
Significant alkali-metal-doped effects on the structure and the first hyperpolarizability (beta(0)) of effective multi-nitrogen complexant tris[(2-imidazolyl)methyl] amine (TIMA) are investigated. Three imidazoles of TIMA like three blades of propeller connect with methyls by the C-C single bonds. Because of the three C-C single-bond cooperative rotations, the TIMA behaves with great flexibility, and it is a high-performance multi-nitrogen complexant for the alkali metal doping. Thus, the new complexes A(m)-TIMA (A(m) = Li, Na, and K) with electride characteristic have diffuse excess electron than the reported electride-type system due to the strong interaction between the complexant TIMA and alkali metal. For the first hyperpolarizability, three engaging electrides A(m)-TIMA with the diffuse excess electrons exhibit considerably large beta(0) values using the MP2 (full) method and the beta(0) values of new electrides are greatly larger (3,464-29,705 times) than that (338 au) of TIMA. Surprisingly, the K-TIMA sets a new record beta(0) value to be 1.00 x 10(7) au which far exceeds than that (3,694-76,978 au) of the reported electride-type system Li@ calix[4]pyrrole (J Am Chem Soc 127:10977-10981, 2005) and Li-n-H-(CF2-CH2)(3)-H (n = 1, 2) (J Am Chem Soc 129: 2967-2970, 2007) and 31,123 au of the organometallic system (J Am Chem Soc 121: 4047-4053, 1999) Ru (trans-4,4'-diethylaminostyryl-2,2'-bipyridine)(3)(2+), as well as 1.23 x 10(6) au of the large donor-CNT systems (Nano Lett 8: 2814-2818, 2008). Clearly, the alkali-metal-doped effect on the first hyperpolarizability is very dramatic for the high-performance multi-nitrogen complexant TIMA. Considering simple possibility from molecule to material, the beta(0) values of optimized Li-TIMA-dimer and Li-TIMA-tetramer are investigated by BHandHLYP method. Interestingly, results show that the order of beta(0) value is Li-TIMA-monomer < Li-TIMA-dimer < Li-TIMA-tetramer. So the new three-propeller-blade-shaped electrides can be considered as candidates for high-performance nonlinear optical materials.