I believe the exact sentence by Searle in the Chinese Room paper was 'syntax is not enough for semantics'. He made the meaning of the sentence more precise by proposing a case in which the syntax of a language is perfectly operated without any semantical comprehension arising from the process. Now, semantics in Searle's sense is some mental comprehension and ...
Matilde Marcolli is also worth mentioning here (especially since the OP is a computer scientist according to his profile). See the two linguistics classes she taught before and the references thereof: