Koszuality of the $\mathcal V^{(d)}$ dioperad

Define a $\mathcal V^{(d)}$-algebra as an associative algebra with a symmetric and invariant co-inner product of degree $d$. Here, we consider $\mathcal V^{(d)}$ as a dioperad which includes operations with zero inputs. We show that the quadratic dual of $\mathcal V^{(d)}$ is $(\mathcal V^{(d)})^!=\mathcal V^{(-d)}$ and prove that $\mathcal V^{(d)}$ is Koszul. We also show that the corresponding properad is not Koszul contractible.