  A quantum symmetric pair consists of a quantum group $\mathbf U$ and its
coideal subalgebra ${\mathbf U}^{\imath}_{{\boldsymbol{\varsigma}}}$ (called an
$\imath$quantum group) with parameters ${\boldsymbol{\varsigma}}$. In this
note, we use the derived Hall algebras of 1-periodic complexes to realize the
$\imath$quantum groups ${\mathbf U}^{\imath}_{{\boldsymbol{\varsigma}}}$ of
split type.
