2 -( 4 - hexylphenyl ) ethynyl ) trimethylsilane ( 4 a ) 1 H NMR ( CDCl 3 , 300 ㎒): δ 7 . 51 - 7 . 48 ppm ( d , 2 H , J = 8 . 18 ㎐), 7 . 20 - 7 . 18 ppm ( d , 2 H , J = 8 . 14 ㎐), 2 . 70 - 2 . 65 ppm ( t , 2 H , J = 7 . 69 ㎐), 1 . 69 - 1 . 66 ppm ( m , 2 H ) , 1 . 14 ppm ( m , 6 H ) , 1 . 01 - 0 . 99 ppm ( t , 3 H , J = 6 . 77 ㎐), 0 . 38 ppm ( s , 9 H )