Impact investing focuses on putting money to work in a way that has a specific, measurable and positive benefit to society or the environment.
Charitable donations however are an altogether seperate issue.
For example if you are passionate about education in a third world country you may want to consider placing investment monies into a fund that targets companies or projects that are working towards delivering quality education in such countries.
The types of companies involved with impact investing tend to be small companies with clear social goals - specialist fund managers typically operate in this market segment.