Learn French: L'architecte propose de nouveaux matériaux, dont le bois. - The architect proposes new materials, including wood.

Dont literally translates to "of which" or "of whom". When you mention a broad category (like de nouveaux matériaux) and want to highlight a specific example within that group, French uses dont to introduce the subset. You can think of it as saying "new materials, of which wood (is one)".

Why is it de nouveaux matériaux instead of des nouveaux matériaux?

This is a classic grammar rule: when an adjective comes before a plural noun, the plural indefinite article des shortens to de. Since nouveaux precedes matériaux, des becomes de. Note that in casual spoken French, you will still often hear people say des nouveaux.

Is the de after propose part of the verb structure, like proposer de?

No, it's not part of the verb here! When offering a noun (a thing), proposer takes a direct object (proposer quelque chose). The de belongs entirely to de nouveaux matériaux. You only use proposer de when you are proposing an action, followed by an infinitive verb (like proposer de manger).

Why do we say dont le bois instead of just dont bois to match "including wood"?