ZnC3N4H4O3 crystallizes in the monoclinic P2/c space group. There are two inequivalent Zn sites. In the first Zn site, Zn(1) is bonded in a trigonal bipyramidal geometry to one N(3), one N(8), one O(2), one O(3), and one O(5) atom. The Zn(1)-N(3) bond length is 2.07 Å. The Zn(1)-N(8) bond length is 2.02 Å. The Zn(1)-O(2) bond length is 2.14 Å. The Zn(1)-O(3) bond length is 2.13 Å. The Zn(1)-O(5) bond length is 2.00 Å. In the second Zn site, Zn(2) is bonded in a trigonal bipyramidal geometry to one N(4), one N(7), one O(1), one O(4), and one O(6) atom. The Zn(2)-N(4) bond length is 2.07 Å. The Zn(2)-N(7) bond length is 2.02 Å. The Zn(2)-O(1) bond length is 2.14 Å. The Zn(2)-O(4) bond length is 2.13 Å. The Zn(2)-O(6) bond length is 2.00 Å. There are six inequivalent C sites. In the first C site, C(1) is bonded in a distorted trigonal planar geometry to one C(3), one N(1), and one N(7) atom. The C(1)-C(3) bond length is 1.49 Å. The C(1)-N(1) bond length is 1.34 Å. The C(1)-N(7) bond length is 1.35 Å. In the second C site, C(2) is bonded in a distorted trigonal planar geometry to one C(4), one N(2), and one N(8) atom. The C(2)-C(4) bond length is 1.49 Å. The C(2)-N(2) bond length is 1.34 Å. The C(2)-N(8) bond length is 1.35 Å. In the third C site, C(3) is bonded in a distorted water-like geometry to one C(1); one H(5,6); and one H(7,8) atom. The C(3)-H(5,6) bond length is 1.09 Å. The C(3)-H(7,8) bond length is 1.10 Å. In the fourth C site, C(4) is bonded in a distorted water-like geometry to one C(2); one H(5,6); and one H(7,8) atom. The C(4)-H(5,6) bond length is 1.09 Å. The C(4)-H(7,8) bond length is 1.10 Å. In the fifth C site, C(5) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(5) atom. The C(5)-O(1) bond length is 1.26 Å. The C(5)-O(5) bond length is 1.28 Å. In the sixth C site, C(6) is bonded in a distorted bent 120 degrees geometry to one O(2) and one O(6) atom. The C(6)-O(2) bond length is 1.26 Å. The C(6)-O(6) bond length is 1.28 Å. There are eight inequivalent N sites. In the first N site, N(1) is bonded in a distorted single-bond geometry to one C(1), one N(3), and one H(2) atom. The N(1)-N(3) bond length is 1.35 Å. The N(1)-H(2) bond length is 1.74 Å. In the second N site, N(2) is bonded in a distorted single-bond geometry to one C(2), one N(4), and one H(1) atom. The N(2)-N(4) bond length is 1.35 Å. The N(2)-H(1) bond length is 1.74 Å. In the third N site, N(3) is bonded in a distorted trigonal planar geometry to one Zn(1), one N(1), and one N(5) atom. The N(3)-N(5) bond length is 1.31 Å. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Zn(2), one N(2), and one N(6) atom. The N(4)-N(6) bond length is 1.31 Å. In the fifth N site, N(5) is bonded in a water-like geometry to one N(3) and one N(7) atom. The N(5)-N(7) bond length is 1.34 Å. In the sixth N site, N(6) is bonded in a water-like geometry to one N(4) and one N(8) atom. The N(6)-N(8) bond length is 1.34 Å. In the seventh N site, N(7) is bonded in a distorted trigonal planar geometry to one Zn(2), one C(1), and one N(5) atom. In the eighth N site, N(8) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(2), and one N(6) atom. There are six inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one N(2) and one O(3) atom. The H(1)-O(3) bond length is 1.01 Å. In the second H site, H(2) is bonded in a single-bond geometry to one N(1) and one O(4) atom. The H(2)-O(4) bond length is 1.01 Å. In the third H site, H(3) is bonded in a single-bond geometry to one O(3) atom. The H(3)-O(3) bond length is 0.97 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(4) atom. The H(4)-O(4) bond length is 0.97 Å. In the fifth H site, H(5,6) is bonded in a single-bond geometry to one C(3) atom. In the sixth H site, H(7,8) is bonded in a single-bond geometry to one C(3) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Zn(2) and one C(5) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to one Zn(1) and one C(6) atom. In the third O site, O(3) is bonded in a distorted water-like geometry to one Zn(1), one H(1), and one H(3) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Zn(2), one H(2), and one H(4) atom. In the fifth O site, O(5) is bonded in a bent 120 degrees geometry to one Zn(1) and one C(5) atom. In the sixth O site, O(6) is bonded in a bent 120 degrees geometry to one Zn(2) and one C(6) atom. Linkers: 8 [O]C(=O)CC1=NN=N[N]1. Metal clusters: 2 O.O.O.O.[C]1O[Zn]O[C]O[Zn]O[C]O[Zn]O[C]O[Zn]O1. The MOF has largest included sphere 2.43 A, density 2.22 g/cm3, surface area 3171.42 m2/g, accessible volume 0.06 cm3/g