Which experiments prove that syntax isn't enough to generate semantics?

I'm sorry but I don't understand your question at all. Semantics is the study of the meaning of words and I don't see any relationship to syntax at all. Turing was a mathmatician and if you mean employing the use of his hypothetical machine it had to do with mathmatical computations. Somewhere in all of this there must be a connection but I don't see it. Could you clarify your intention please or restate the question? Thank you and Happy Thursday Fejron! :)

You can find a very extensive discussion of the Chinese Room Argument in relation to the Turing Test in the Wikipedia article. The Turing test does something different.

For those who don't know what you are talking about, here a presentation:

1) "The Turing test is a proposal for a test of a machine's ability to demonstrate intelligence. It proceeds as follows: a human judge engages in a natural language conversation with one human and one machine, each of which tries to appear human. All participants are placed in isolated locations. If the judge cannot reliably tell the machine from the human, the machine is said to have passed the test. In order to test the machine's intelligence rather than its ability to render words into audio, the conversation is limited to a text-only channel such as a computer keyboard and screen."
Source and further information:
http://en.wikipedia.org/wiki/Turing_test


2) "Chinese room thought experiment:
Searle's thought experiment begins with this hypothetical premise: suppose that artificial intelligence research has succeeded in constructing a computer that behaves as if it understands Chinese. It takes Chinese characters as input and, by following the instructions of a computer program, produces other Chinese characters, which it presents as output. Suppose, says Searle, that this computer performs its task so convincingly that it comfortably passes the Turing test: it convinces a human Chinese speaker that the program is itself a human Chinese speaker. To all of the questions that the human asks, it makes appropriate responses, such that any Chinese speaker would be convinced that he or she is talking to another Chinese-speaking human being.
Some proponents of artificial intelligence would conclude that the computer "understands" Chinese. This conclusion, a position he refers to as strong AI, is the target of Searle's argument.

Searle then asks the reader to suppose that he is in a closed room and that he has a book with an English version of the aforementioned computer program, along with sufficient paper, pencils, erasers and filing cabinets. He can receive Chinese characters (perhaps through a slot in the door), process them according to the program's instructions, and produce Chinese characters as output. As the computer had passed the Turing test this way, it is fair, says Searle, to deduce that the human operator will be able to do so as well, simply by running the program manually.

Searle asserts that there is no essential difference between the role the computer plays in the first case and the role the human operator plays in the latter. Each is simply following a program, step-by-step, which simulates intelligent behavior. And yet, Searle points out, the human operator does not understand a word of Chinese. Since it is obvious that he does not understand Chinese, Searle argues, we must infer that the computer does not understand Chinese either.
Searle argues that without "understanding" (what philosophers call "intentionality"), we cannot describe what the machine is doing as "thinking". Because it does not think, it does not have a "mind" in anything like the normal sense of the word, according to Searle. Therefore, he concludes, "strong AI" is mistaken.

- History:
Searle's argument first appeared in his paper "Minds, Brains, and Programs", published in Behavioral and Brain Sciences in 1980. It eventually became the journal's "most influential target article", generating an enormous number of commentaries and responses in the ensuing decades.

Most of the discussion consists of attempts to refute it. "The overwhelming majority," notes BBS editor Stevan Harnad, "still think that the Chinese Room Argument is dead wrong." The sheer volume of the literature that has grown up around it inspired Pat Hayes to quip that the field of cognitive science ought to be redefined as "the ongoing research program of showing Searle's Chinese Room Argument to be false."
Despite the controversy (or perhaps because of it), the paper has become "something of a classic in cognitive science," according to Harnad. Varol Akman agrees, and has described Searle's paper as "an exemplar of philosophical clarity and purity"."

"(A3) "Syntax by itself is neither constitutive of nor sufficient for semantics."
This is what the Chinese room argument is intended to prove: the Chinese room has syntax (because there is a man in there moving symbols around). The Chinese room has no semantics (because, according to Searle, there is no one or nothing in the room that understands what the symbols mean). Therefore, having syntax is not enough to generate semantics."
Source and further information:
http://en.wikipedia.org/wiki/Chinese_room

Further information:
http://www.scholarpedia.org/article/Chinese_room_argument


3) "In conclusion, we can say that Searle was perhaps right in arguing that mere syntactical rules do not suffice for understanding, but also that he was definitely wrong in assuming that a computer, successfully imitating our linguistic abilities, can be limited solely to syntactical rules (the Chinese room). Such a computer will have to interact with things in the world, be it a watch fixed inside it or perceptual information available via various instruments, in order to achieve the required competence. ‘Computer programs are formal (syntactic)’ (Searle 1990, p. 27), that’s for sure; but the computers in which they are realized make contact with the surrounding world in various ways, essential for their functioning. Accordingly, the formality of computer programs does not prove that the computers themselves lack understanding."
Source and further information:
http://web.ceu.hu/phil/benyami/A%20Note%20on%20the%20Chinese%20Room.pdf