ErZnC12H7(NO2)4 crystallizes in the monoclinic C2/c space group. Er(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(7), one O(8), and two equivalent O(6) atoms. The Er(1)-O(2) bond length is 2.27 Å. The Er(1)-O(3) bond length is 2.21 Å. The Er(1)-O(7) bond length is 2.27 Å. The Er(1)-O(8) bond length is 2.44 Å. There is one shorter (2.40 Å) and one longer (2.52 Å) Er(1)-O(6) bond length. Zn(1) is bonded in an octahedral geometry to one N(1), one N(2), one N(4), one O(1), one O(4), and one O(5) atom. The Zn(1)-N(1) bond length is 2.07 Å. The Zn(1)-N(2) bond length is 2.13 Å. The Zn(1)-N(4) bond length is 2.08 Å. The Zn(1)-O(1) bond length is 2.25 Å. The Zn(1)-O(4) bond length is 2.18 Å. The Zn(1)-O(5) bond length is 2.21 Å. There are twelve inequivalent C sites. In the first C site, C(1) is bonded in a distorted single-bond geometry to one C(6) and one N(4) atom. The C(1)-C(6) bond length is 1.39 Å. The C(1)-N(4) bond length is 1.37 Å. In the second C site, C(2) is bonded in a bent 120 degrees geometry to one C(6), one O(2), and one O(5) atom. The C(2)-C(6) bond length is 1.48 Å. The C(2)-O(2) bond length is 1.27 Å. The C(2)-O(5) bond length is 1.26 Å. In the third C site, C(3) is bonded in a trigonal non-coplanar geometry to one C(9), one H(2), one H(5), and one H(6) atom. The C(3)-C(9) bond length is 1.49 Å. The C(3)-H(2) bond length is 0.96 Å. The C(3)-H(5) bond length is 0.96 Å. The C(3)-H(6) bond length is 0.96 Å. In the fourth C site, C(4) is bonded in a distorted single-bond geometry to one C(11), one C(12), and one N(3) atom. The C(4)-C(11) bond length is 1.38 Å. The C(4)-C(12) bond length is 1.48 Å. The C(4)-N(3) bond length is 1.37 Å. In the fifth C site, C(5) is bonded in a trigonal non-coplanar geometry to one C(10), one H(3), one H(4), and one H(7) atom. The C(5)-C(10) bond length is 1.49 Å. The C(5)-H(3) bond length is 0.96 Å. The C(5)-H(4) bond length is 0.96 Å. The C(5)-H(7) bond length is 0.96 Å. In the sixth C site, C(6) is bonded in a distorted single-bond geometry to one C(1), one C(2), and one N(1) atom. The C(6)-N(1) bond length is 1.37 Å. In the seventh C site, C(7) is bonded in a distorted bent 120 degrees geometry to one O(1) and one O(7) atom. The C(7)-O(1) bond length is 1.25 Å. The C(7)-O(7) bond length is 1.28 Å. In the eighth C site, C(8) is bonded in a distorted bent 120 degrees geometry to one O(3) and one O(4) atom. The C(8)-O(3) bond length is 1.27 Å. The C(8)-O(4) bond length is 1.24 Å. In the ninth C site, C(9) is bonded in a distorted trigonal planar geometry to one C(3), one N(2), and one N(3) atom. The C(9)-N(2) bond length is 1.33 Å. The C(9)-N(3) bond length is 1.35 Å. In the tenth C site, C(10) is bonded in a distorted trigonal planar geometry to one C(5), one N(1), and one N(4) atom. The C(10)-N(1) bond length is 1.34 Å. The C(10)-N(4) bond length is 1.34 Å. In the eleventh C site, C(11) is bonded in a distorted single-bond geometry to one C(4) and one N(2) atom. The C(11)-N(2) bond length is 1.38 Å. In the twelfth C site, C(12) is bonded in a bent 120 degrees geometry to one C(4), one O(6), and one O(8) atom. The C(12)-O(6) bond length is 1.26 Å. The C(12)-O(8) bond length is 1.26 Å. There are four inequivalent N sites. In the first N site, N(1) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(10), and one C(6) atom. In the second N site, N(2) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(11), and one C(9) atom. In the third N site, N(3) is bonded in a trigonal planar geometry to one C(4), one C(9), and one H(1) atom. The N(3)-H(1) bond length is 0.88 Å. In the fourth N site, N(4) is bonded in a distorted trigonal planar geometry to one Zn(1), one C(1), and one C(10) atom. There are seven inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one N(3) atom. In the second H site, H(2) is bonded in a single-bond geometry to one C(3) atom. In the third H site, H(3) is bonded in a single-bond geometry to one C(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one C(5) atom. In the fifth H site, H(5) is bonded in a single-bond geometry to one C(3) atom. In the sixth H site, H(6) is bonded in a single-bond geometry to one C(3) atom. In the seventh H site, H(7) is bonded in a single-bond geometry to one C(5) atom. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a bent 120 degrees geometry to one Zn(1) and one C(7) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Er(1) and one C(2) atom. In the third O site, O(4) is bonded in a bent 120 degrees geometry to one Zn(1) and one C(8) atom. In the fourth O site, O(5) is bonded in a bent 120 degrees geometry to one Zn(1) and one C(2) atom. In the fifth O site, O(6) is bonded in a distorted single-bond geometry to two equivalent Er(1) and one C(12) atom. In the sixth O site, O(7) is bonded in a bent 150 degrees geometry to one Er(1) and one C(7) atom. In the seventh O site, O(8) is bonded in a distorted single-bond geometry to one Er(1) and one C(12) atom. In the eighth O site, O(3) is bonded in a bent 150 degrees geometry to one Er(1) and one C(8) atom. Linkers: 4 Cc1nc(C([O])=O)c(C([O])=O)[nH]1 ,2 CC1=N[C](C([O])=O)C(C([O])=O)=N1 ,2 CC1=NC(C([O])=O)=C(C([O])=O)[N]1. Metal clusters: 4 [Er] ,4 [Zn]. The MOF has largest included sphere 5.96 A, density 1.95 g/cm3, surface area 2912.60 m2/g, accessible volume 0.20 cm3/g