No, all programming languages have to be provided with a semantics. Syntax alone provides no information on how to run any program at any level. That includes Turing machines and all other formal systems. The syntax of Turing machine programs (lines of quintuples of the form state x symbol -> symbol x shift x state) does not tell you how to run a Turing machine program on a Turing machine. I have to admit that I don't really see how syntax being insufficient for semantics is an argument against machine consciousness. It's a very good argument for including semantics in an AI, but not much else.