Nematicity and superconductivity in orthorhombic superconductor Na0.35(C3N2H10)0.426Fe2Se2

$\mathrm{N}{\mathrm{a}}_{0.35}{({\mathrm{C}}_{3}{\mathrm{N}}_{2}{\mathrm{H}}_{10})}_{0.426}\mathrm{F}{\mathrm{e}}_{2}\mathrm{S}{\mathrm{e}}_{2}$ exhibits a large orthorhombic distortion at room temperature without magnetic ordering, hence providing an ideal platform to investigate the correlation between nematicity and superconductivity. We show that its nematicity is stabilized by ``nematic'' ordered 1,3-diaminopropane (1,3- DIA) molecules in between the FeSe layers, and the C2 twofold rotational symmetry is preserved down to 10 K without phase transition. The superconductivity occurs at 46.5 K even though the orthorhombic distortion is much larger than that for \ensuremath{\beta}-FeSe and most of the other pnictide superconductors at low temperatures. First principles calculations reveal that this ``artificial'' orthorhombic distortion has a selective effect on the band structure, which behaves differently on splitting the iron $3{d}_{xz}$ and $3{d}_{yz}$ orbitals around the \cyrchar\CYRG{} and M points in the Brillouin zone. Our finding strongly supports that the nematic state is irrelevant to the emergent superconductivity, at least in high-${T}_{c}$ iron selenide superconductors.