[kamiyu]

I saw some people doing work molecular crystal.

Could you briefly tell me:

1) What is molecular crystal?

2) Why it matters? Advantages?

Thanks

[Arkcon]

I saw some people doing work molecular crystal.

Really?  What did you see?  What were they doing?

Could you briefly tell me:

1) What is molecular crystal?

I can't.  But maybe someone else on these boards can.  However, a Wikipedia search redirects to Molecular solid, which is a common enough term.  Are you using jargon, or an archaic term for something common?  Again, you say you saw it.  So what did you see?

2) Why it matters? Advantages?

Again, can you provide us with some context?

[kamiyu]

I saw the term in a conference/meeting about material science.

I am working in novel advanced materials.

The title of the presentation is "molecular crystals"

I guess that the guy is going to say something like the application of the molecular crystals (which should mean materials that are crystalline and is made of small molecules)

[mjc123]

"Molecular crystals" means in general what you say, i.e. crystalline materials consisting of small molecules, as distinct from e.g. ionic crystals such as NaCl. These are very common; most organic compounds in the solid state form molecular crystals. These are in no sense "novel advanced materials".

However, some people seem to use the term in a narrower sense, e.g. there is a journal "Molecular Crystals and Liquid Crystals", where (judging from a quick look at a few abstracts) "molecular crystals" seems to mean, or at least to focus on, molecular crystals in which the molecules are organised into larger scale structures by specific intermolecular interactions stronger than van der Waals forces but weaker than covalent bonds, e.g. hydrogen bonds or π - π interactions. These materials can have interesting properties e.g. optical or electronic. Perhaps this is what your presentation is about. But as there are already terms for this sort of thing, such as "supramolecular chemistry" and "self-assembled structures", I see no need to appropriate "molecular crystals" to mean a small subset of itself.