GdC18P3H21(NO4)3 crystallizes in the triclinic P-1 space group. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded to two equivalent O(4), two equivalent O(5), and two equivalent O(6) atoms to form GdO6 octahedra that share corners with two equivalent P(1)CO3 tetrahedra, corners with two equivalent P(2)CO3 tetrahedra, and corners with two equivalent P(3)CO3 tetrahedra. Both Gd(1)-O(4) bond lengths are 2.27 Å. Both Gd(1)-O(5) bond lengths are 2.27 Å. Both Gd(1)-O(6) bond lengths are 2.27 Å. In the second Gd site, Gd(2) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form GdO6 octahedra that share corners with two equivalent P(1)CO3 tetrahedra, corners with two equivalent P(2)CO3 tetrahedra, and corners with two equivalent P(3)CO3 tetrahedra. Both Gd(2)-O(1) bond lengths are 2.29 Å. Both Gd(2)-O(2) bond lengths are 2.29 Å. Both Gd(2)-O(3) bond lengths are 2.29 Å. There are twelve inequivalent C sites. In the first C site, C(1) is bonded in a distorted bent 120 degrees geometry to one N(1) and one H(1,2,3) atom. The C(1)-N(1) bond length is 1.35 Å. The C(1)-H(1,2,3) bond length is 1.09 Å. In the second C site, C(2) is bonded in a distorted bent 120 degrees geometry to one N(2) and one H(1,2,3) atom. The C(2)-N(2) bond length is 1.35 Å. The C(2)-H(1,2,3) bond length is 1.09 Å. In the third C site, C(3) is bonded in a distorted bent 120 degrees geometry to one N(3) and one H(1,2,3) atom. The C(3)-N(3) bond length is 1.35 Å. The C(3)-H(1,2,3) bond length is 1.09 Å. In the fourth C site, C(4,5,6) is bonded in a distorted single-bond geometry to one C(7,8,9) and one H(4,5,6) atom. The C(4,5,6)-C(7,8,9) bond length is 1.40 Å. The C(4,5,6)-H(4,5,6) bond length is 1.09 Å. In the fifth C site, C(7,8,9) is bonded in a trigonal planar geometry to one C(10,11,12); one C(16); and one C(4,5,6) atom. The C(7,8,9)-C(10,11,12) bond length is 1.41 Å. The C(7,8,9)-C(16) bond length is 1.49 Å. In the sixth C site, C(10,11,12) is bonded in a distorted single-bond geometry to one C(13); one C(7,8,9); and one H(7,8,9) atom. The C(10,11,12)-C(13) bond length is 1.38 Å. The C(10,11,12)-H(7,8,9) bond length is 1.09 Å. In the seventh C site, C(13) is bonded in a distorted trigonal planar geometry to one C(10,11,12); one N(1); and one H(10,11,12) atom. The C(13)-N(1) bond length is 1.35 Å. The C(13)-H(10,11,12) bond length is 1.09 Å. In the eighth C site, C(14) is bonded in a distorted trigonal planar geometry to one C(10,11,12); one N(2); and one H(10,11,12) atom. The C(14)-C(10,11,12) bond length is 1.38 Å. The C(14)-N(2) bond length is 1.35 Å. The C(14)-H(10,11,12) bond length is 1.09 Å. In the ninth C site, C(15) is bonded in a distorted trigonal planar geometry to one C(10,11,12); one N(3); and one H(10,11,12) atom. The C(15)-C(10,11,12) bond length is 1.38 Å. The C(15)-N(3) bond length is 1.35 Å. The C(15)-H(10,11,12) bond length is 1.09 Å. In the tenth C site, C(16) is bonded in a 2-coordinate geometry to one C(7,8,9); one P(1); one H(13,14,15); and one O(10) atom. The C(16)-P(1) bond length is 1.88 Å. The C(16)-H(13,14,15) bond length is 1.11 Å. The C(16)-O(10) bond length is 1.42 Å. In the eleventh C site, C(17) is bonded in a 2-coordinate geometry to one C(7,8,9); one P(2); one H(13,14,15); and one O(11) atom. The C(17)-C(7,8,9) bond length is 1.49 Å. The C(17)-P(2) bond length is 1.88 Å. The C(17)-H(13,14,15) bond length is 1.11 Å. The C(17)-O(11) bond length is 1.42 Å. In the twelfth C site, C(18) is bonded in a 2-coordinate geometry to one C(7,8,9); one P(3); one H(13,14,15); and one O(12) atom. The C(18)-C(7,8,9) bond length is 1.49 Å. The C(18)-P(3) bond length is 1.88 Å. The C(18)-H(13,14,15) bond length is 1.11 Å. The C(18)-O(12) bond length is 1.42 Å. There are three inequivalent P sites. In the first P site, P(1) is bonded to one C(16), one O(1), one O(4), and one O(7) atom to form distorted PCO3 tetrahedra that share  a cornercorner with one Gd(1)O6 octahedra and  a cornercorner with one Gd(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-45°. The P(1)-O(1) bond length is 1.56 Å. The P(1)-O(4) bond length is 1.52 Å. The P(1)-O(7) bond length is 1.52 Å. In the second P site, P(2) is bonded to one C(17), one O(2), one O(5), and one O(8) atom to form distorted PCO3 tetrahedra that share  a cornercorner with one Gd(1)O6 octahedra and  a cornercorner with one Gd(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-45°. The P(2)-O(2) bond length is 1.56 Å. The P(2)-O(5) bond length is 1.52 Å. The P(2)-O(8) bond length is 1.52 Å. In the third P site, P(3) is bonded to one C(18), one O(3), one O(6), and one O(9) atom to form distorted PCO3 tetrahedra that share  a cornercorner with one Gd(1)O6 octahedra and  a cornercorner with one Gd(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-45°. The P(3)-O(3) bond length is 1.56 Å. The P(3)-O(6) bond length is 1.52 Å. The P(3)-O(9) bond length is 1.52 Å. There are three inequivalent N sites. In the first N site, N(1) is bonded in a trigonal planar geometry to one C(1), one C(13), and one H(17) atom. The N(1)-H(17) bond length is 1.10 Å. In the second N site, N(2) is bonded in a trigonal planar geometry to one C(14), one C(2), and one H(18) atom. The N(2)-H(18) bond length is 1.10 Å. In the third N site, N(3) is bonded in a trigonal planar geometry to one C(15), one C(3), and one H(16) atom. The N(3)-H(16) bond length is 1.11 Å. There are eleven inequivalent H sites. In the first H site, H(1,2,3) is bonded in a single-bond geometry to one C(1) atom. In the second H site, H(4,5,6) is bonded in a single-bond geometry to one C(4,5,6) atom. In the third H site, H(7,8,9) is bonded in a single-bond geometry to one C(10,11,12) atom. In the fourth H site, H(10,11,12) is bonded in a single-bond geometry to one C(13) atom. In the fifth H site, H(13,14,15) is bonded in a single-bond geometry to one C(16) atom. In the sixth H site, H(16) is bonded in a linear geometry to one N(3) and one O(7) atom. The H(16)-O(7) bond length is 1.44 Å. In the seventh H site, H(17) is bonded in a linear geometry to one N(1) and one O(8) atom. The H(17)-O(8) bond length is 1.44 Å. In the eighth H site, H(18) is bonded in a linear geometry to one N(2) and one O(9) atom. The H(18)-O(9) bond length is 1.44 Å. In the ninth H site, H(19) is bonded in a single-bond geometry to one O(10) and one O(2) atom. The H(19)-O(10) bond length is 1.00 Å. The H(19)-O(2) bond length is 1.71 Å. In the tenth H site, H(20) is bonded in a single-bond geometry to one O(11) and one O(3) atom. The H(20)-O(11) bond length is 1.00 Å. The H(20)-O(3) bond length is 1.71 Å. In the eleventh H site, H(21) is bonded in a single-bond geometry to one O(1) and one O(12) atom. The H(21)-O(1) bond length is 1.71 Å. The H(21)-O(12) bond length is 1.00 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Gd(2), one P(1), and one H(21) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Gd(2), one P(2), and one H(19) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Gd(2), one P(3), and one H(20) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Gd(1) and one P(1) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Gd(1) and one P(2) atom. In the sixth O site, O(6) is bonded in a bent 150 degrees geometry to one Gd(1) and one P(3) atom. In the seventh O site, O(7) is bonded in a bent 120 degrees geometry to one P(1) and one H(16) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one P(2) and one H(17) atom. In the ninth O site, O(9) is bonded in a bent 120 degrees geometry to one P(3) and one H(18) atom. In the tenth O site, O(10) is bonded in a water-like geometry to one C(16) and one H(19) atom. In the eleventh O site, O(11) is bonded in a water-like geometry to one C(17) and one H(20) atom. In the twelfth O site, O(12) is bonded in a water-like geometry to one C(18) and one H(21) atom. Linkers: 3 [O]P([O])(=O)[C@@H](O)C1=C[CH]NC=C1 ,3 [O]P([O])(=O)[C@H](O)C1=C[CH]NC=C1. Metal clusters: 2 [Gd]. The MOF has largest included sphere 3.30 A, density 1.73 g/cm3, surface area 3543.87 m2/g, accessible volume 0.17 cm3/g