[Grammar] punctuation with thus, therefore

When "thus" or "therefore" introduce a dependent clause, is a comma between clauses needed? Here's my problematic sentence:

The foundation manages private gifts for the benefit of the university thus assuring the donor that the purpose for which funds were donated will be honored.

Better?: ... university, thus assuring the donor ...

or: ... university, thus, assuring the donor ...

or eliminate "thus"?: ... university, assuring the donor ...

[susiedqq]

The sentence is awkard, and I suggest you avoid the "thus"

Re-writing it:

To assure donors the purpose of their donations will be honored, the foundation will manage private gifts to benefit the university.

But as a possible donor, it still does not make me feel good.

How about:

Because the Foundation manages private gifts for the benefit of the university, each donor is assured that the purpose of their gift will be honored.