In this paper, the first new organometallic mechanoluminescent materials are reported.
Group 4 metal complexes including $M({η^5;η^1-CpCMe_2CB_{10}H_{10}C)_2$ (M = Ti; 2, Zr; 3, Hf; 4) , $Cp^*M(η^5;η1-CpCMe_2CB_{10}H_{10}C)Cl$, (M = Ti; 5, Zr; 6, Hf; 7) and $Cp^*M(η^5-CpCMe_2CB_{10}H_{10}CH)Cl_2$, (M = Ti; 8, Zr; 9, Hf; 10) were synthesized.
Complex 3 and 4 showed mechanoluminescence (ML), but 2, 5, 6, 7, 8, 9 and 10 had no ML. These complex systems were explored based on the correlation between the ML activity and the unit cell polarity. Unit cell polarity is related to the molecular net dipole moment, which was calculated by HyperChem program. Noncentrosymmetric crystalline systems (2, 3 and 4) had large net dipole moment values, but centrosymmetric crystalline systems (5, 6, 7, 8, 9 and 10) had very small values. These facts comparatively coincide with experimental results. Exception of complex 2 was discussed in text.
