The　title　compound　was　synthesized　by　employing　high-temperature　solution　reaction　methods　at　840　degrees　C.　Single-crystal　XRD　analysis　showed　that　it　crystallizes　in　the　orthorhombic　noncentrosymmetric　space　group　Fdd2,　with　unit　cell　parameters　a=13.326(3)　angstrom,　b=14.072(3)angstrom,　c=10.238(2)angstrom,　Z=16,　and　V=1919.9(7)　angstrom(3).　It　has　two　independent　and　interpenetrating　3D　frameworks　consisting　of　[B4O9](6-)　groups　bridged　by　O　atoms,　with　intersecting　channels　occupied　by　Na+　and　Li+　cations.　The　IR　spectrum　further　confirmed　the　presence　of　both　BO3　and　BO4　groups.　UV-vis　diffuse　reflectance　spectrum　showed　a　band　gap　of　about　3.88　eV.　Solid-state　fluorescence　spectrum　exhibited　the　maximum　emission　peak　at　around　337.8　nm.　Furthermore　we　have　performed　theoretical　calculations　by　employing　the　state-of-the-art　all-electron　full　potential　linearized　augmented　plane　wave　(FP-LAPW)　method　to　solve　the　Kohn　Sham　equations.　We　have　optimized　the　atomic　positions　taken　from　our　XRD　data　by　minimizing　the　forces.　The　optimized　atomic　positions　are　used　to　calculate　the　electronic　band　structure,　the　atomic　site-decomposed　density　of　states,　electron　charge　density　and　the　chemical　bonding　features.　The　calculated　electronic　band　structure　and　densities　of　states　suggested　that　this　single　crystal　possesses　a　wide　energy　band　gap　of　about　2.80　eV　using　the　local　density　approximation,　2.91　eV　by　generalized　gradient　approximation,　321　eV　for　the　Engel-Vosko　generalized　gradient　approximation　and　3.81　eV　using　modified　Becke-Johnson　potential　(mBJ).　This　compares　well　with　our　experimentally　measured　energy　band　gap　of　3.88　eV.　From　our　calculated　electron　charge　density　distribution,　we　obtain　an　image　of　the　electron　clouds　that　surround　the　molecules　in　the　average　unit　cell　of　the　crystal.　The　chemical　bonding　features　were　analyzed　and　the　substantial　covalent　interactions　were　observed　between　O　and　O,　B　and　O,　Li　and　O　as　well　as　Na　and　O　atoms.　(C)　2012　Elsevier　B.V.　All　rights　reserved.