Quasi-Hopf algebras associated with sl(2) and complex curves

We construct quasi-Hopf algebras quantizing double extensions of the Manin pairs of Drinfeld, associated to a curve with a meromorphic differential, and the Lie algebra sl(2). This construction makes use of an analysis of the vertex relations for the quantum groups obtained in our earlier work, PBW-type results and computation of $R$-matrices for them; its key step is a factorization of the twist operator relating ``conjugated'' versions of these quantum groups.