"Is it permissible for a Muslim to convert usurious loans into Islamic ones with the intention and by donating a portion of the resulting profits to charitable organizations, whether as a depositor or a borrower, with the aim of purifying the money from usury and benefiting the community? "

Praise be to Allah, what you mentioned does not constitute a legitimate justification for dealing with usurious banks, as good intentions alone are not sufficient if the action contradicts the Sharia (definition). Sins do not turn into acts of obedience by intention, and a good intention does not justify a corrupt action. It is not permissible to deal with usurious banks except in cases of necessity, and whoever receives bank interest must withdraw it and spend it on the interests of Muslims, and it is not permissible to intend bank investment to give the profits to the poor.