う・よう + とするTry to, Attempt to, To be about to

These two expressions are opposite uses of the same structure. Verb[volitional]とする means 'Try to do (A)' or 'Make an attempt at (A)', often with the nuance that the attempt may fail, e.g. 食べようとしたけど、無理だった 'I tried to eat it, but I couldn't.' In contrast, 〜ようとしない means 'Not even try to (A)', e.g. うちの息子は、野菜を食べようとしない 'My son doesn't even try to eat vegetables.'

The grammar point 'Verb[volitional]とする' expresses the speaker's decision or intention to do something, often indicating a plan or goal. In contrast, 'まだ～ていません' is used to express that an action has not yet occurred or a state has not yet been reached, emphasizing the ongoing absence of the action or state.

Both can describe actions about to happen, but with different nuance. るところだ simply states that something is on the verge of occurring. Verb[volitional] + とする adds a sense of intent or effort, and is often used when the action may not actually happen, e.g. 子どもはなんでも食べようとする ('Kids will try to eat anything.'), where 食べるところだ wouldn't be appropriate.

Both of these use Verb [よう], the volitional form. On its own, it expresses a suggestion, e.g. 食べよう ('Let's eat.'). When combined with とする, it shows an attempt to do something, often one that fails, e.g. 食べようとしたけど ('I tried to eat it, but...'). The key difference is suggestion/proposal vs. attempted action.

ようにする (literally, 'do things in such a way as to X') expresses taking care to perform a certain action and often indicates a habitual effort. In contrast, Verb[volitional] + とする implies a one-time attempt to do something, often implying the attempt may not succeed. For example, 毎朝走るようにしている ('I'm making a habit of running every morning.') vs. １０キロ走ろうとしたけど ('I tried to run 10k, but...' implying 'but I couldn't finish', etc.).

Both structures use the volitional verb form to show intent, but differ in whether the outcome is explicitly expressed. 'Verb[volitional]とする' expresses an attempt or intention to do something, e.g. '食べようとする' ('try to eat'). 'Verb[volitional]としたが' implies the attempt was interrupted or failed, e.g. '食べようとしたが、無理だった' ('I tried to eat it, but couldn't').

Verb[volitional]とする and てみる are both translated as 'try', but the former implies attempting something that may not succeed, e.g. 話そうとした ('I tried to speak.'), which implies that maybe the attempt was unsuccessful. In contrast,てみる focuses on trying something to see the result, as in 話してみた ('I tried speaking.'), which has the nuance of doing so to see what it was like.