A new luminescent anionic metal–organic framework based on heterometallic zinc(II)–barium(II) for selective detection of Fe³⁺ and Cu²⁺ ions in aqueous solution

Over the past two decades, the development of novel inorganic–organic hybrid porous crystalline materials or metal–organic frameworks (MOFs) using crystal engineering has provoked significant inter­est due to their potential applications as functional materials. In this context, luminescent MOFs as fluorescence sensors have recently received significant attention for the sensing of ionic species and small mol­ecules. In this work, a new luminescent heterometallic zinc(II)–barium(II)-based anionic metal–organic framework, namely poly[imidazolium [tri­aqua­(μ₆-benzene-1,3,5-tri­carboxyl­ato)bariumtrizinc] tetra­hy­drate], {(C₃H₄N₂)[BaZn₃(C₉H₃O₆)₃(H₂O)₃]·4H₂O}_n (1), was synthesized under hydro­thermal conditions and characterized. Compound 1 presents a three-dimensional framework with an unprecedented (3,5)-connected topology of the point symbol (3.9²).(3³.4².5.9³.10), and exhibits `turn-off' luminescence responses for the Cu²⁺ and Fe³⁺ ions in aqueous solution based on significantly different quenching mechanisms.

Computing details

Data collection: APEX3 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Poly[imidazolium [triaqua(µ₆-benzene-1,3,5-tricarboxylato)bariumtrizinc] tetrahydrate]

Crystal data

(C3H4N2)[BaZn3(C9H3O6)3(H2O)3]·4H2O	Dx = 2.119 Mg m^−3
Mr = 2035.65	Mo Kα radiation, λ = 0.71073 Å
Trigonal, P31c	Cell parameters from 9217 reflections
a = 15.2649 (9) Å	θ = 3.0–29.6°
c = 7.9050 (6) Å	µ = 3.54 mm^−1
V = 1595.2 (2) Å^3	T = 296 K
Z = 1.0	Rhombohedral, colourless
F(000) = 992	0.22 × 0.18 × 0.18 mm

Data collection

Bruker D8 QUEST CMOS PHOTON II diffractometer	2689 independent reflections
Radiation source: sealed x-ray tube, Mo	2617 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
Detector resolution: 7.39 pixels mm^-1	θmax = 28.5°, θmin = 3.0°
φ and ω scans	h = −20→20
Absorption correction: multi-scan (SADABS; Bruker, 2016)	k = −20→20
Tmin = 0.635, Tmax = 0.746	l = −10→10
43027 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.017	w = 1/[σ^2(Fo^2) + (0.0185P)^2 + 0.5728P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.037	(Δ/σ)max < 0.001
S = 1.06	Δρmax = 0.40 e Å^−3
2689 reflections	Δρmin = −0.32 e Å^−3
179 parameters	Absolute structure: Flack x determined using 1256 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
28 restraints	Absolute structure parameter: 0.014 (4)
Primary atom site location: dual

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. The SQUEEZE routine, a part of the PLATON software package, was used to calculate the disorder area and remove the diffraction contribution to afford a set of solvent free diffraction intensities. After subtracting the imidazolium and water contribution, PLATON calculations indicate that the effective pore volume is 181.2 Å3 per unit cell (11.4% out of the 1595.2 Å3 unit cell volume) and contain an estimated 61 electrons. These electrons are attributable to approximately one imidazolium molecule (37 electrons) and two and a half lattice water molecules (24 electrons), presenting in a formula unit. The contents of the removed guest region are not represented in the unit cell contents in the crystal data.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ba1	0.333333	0.666667	0.44450 (6)	0.02565 (9)
Zn1	0.306950	0.353450	0.256960	0.01899 (8)
O1	0.17325 (16)	0.30823 (17)	0.3483 (3)	0.0253 (5)
O2	0.22559 (19)	0.45942 (16)	0.4612 (4)	0.0321 (5)
O3	−0.02007 (18)	0.53505 (17)	0.7338 (3)	0.0253 (5)
O4	−0.18457 (19)	0.42731 (19)	0.6991 (4)	0.0347 (6)
O5	−0.28696 (16)	0.06826 (17)	0.4990 (3)	0.0240 (5)
O6	−0.21362 (18)	0.08612 (17)	0.2541 (3)	0.0288 (5)
O7	0.449 (3)	0.795 (3)	0.736 (5)	0.043 (5)	0.33 (7)
H7A	0.449 (10)	0.848 (9)	0.77 (2)	0.065*	0.33 (7)
H7B	0.510 (6)	0.811 (10)	0.762 (18)	0.065*	0.33 (7)
O7A	0.4257 (18)	0.7960 (13)	0.7464 (17)	0.042 (3)	0.67 (7)
H7AA	0.476 (5)	0.857 (3)	0.731 (8)	0.062*	0.67 (7)
H7AB	0.389 (5)	0.816 (6)	0.799 (8)	0.062*	0.67 (7)
O8	0.333333	0.666667	0.9576 (12)	0.0229 (14)	0.5
H8A	0.385960	0.717590	0.918157	0.034*	0.1667
H8B	0.287900	0.653550	0.883817	0.034*	0.1667
C1	0.1583 (2)	0.3737 (2)	0.4247 (4)	0.0195 (6)
C2	0.0507 (2)	0.3406 (2)	0.4667 (4)	0.0179 (6)
C3	0.0292 (2)	0.4059 (2)	0.5560 (4)	0.0191 (6)
H3	0.081768	0.468367	0.591187	0.023*
C4	−0.0700 (2)	0.3790 (2)	0.5934 (4)	0.0177 (6)
C5	−0.0945 (2)	0.4512 (2)	0.6834 (4)	0.0200 (6)
C6	−0.1486 (2)	0.2844 (2)	0.5458 (4)	0.0189 (6)
H6	−0.214892	0.264853	0.574922	0.023*
C7	−0.1276 (2)	0.2190 (2)	0.4542 (4)	0.0182 (6)
C8	−0.2135 (2)	0.1189 (2)	0.4001 (4)	0.0187 (6)
C9	−0.0290 (2)	0.2474 (2)	0.4126 (4)	0.0187 (6)
H9	−0.015513	0.204442	0.348488	0.022*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ba1	0.01573 (9)	0.01573 (9)	0.0455 (2)	0.00786 (5)	0.000	0.000
Zn1	0.01347 (15)	0.01515 (16)	0.02823 (17)	0.00706 (13)	0.00269 (13)	0.00267 (13)
O1	0.0174 (10)	0.0278 (12)	0.0326 (13)	0.0127 (9)	0.0071 (9)	0.0003 (9)
O2	0.0178 (11)	0.0197 (10)	0.0512 (15)	0.0038 (10)	0.0053 (10)	0.0008 (11)
O3	0.0283 (12)	0.0197 (11)	0.0325 (13)	0.0153 (10)	−0.0067 (9)	−0.0069 (9)
O4	0.0262 (13)	0.0253 (12)	0.0570 (16)	0.0162 (11)	0.0151 (12)	0.0042 (11)
O5	0.0157 (10)	0.0203 (11)	0.0278 (11)	0.0030 (9)	0.0031 (9)	0.0001 (9)
O6	0.0309 (13)	0.0196 (11)	0.0234 (11)	0.0033 (10)	0.0018 (10)	−0.0042 (9)
O7	0.029 (9)	0.040 (7)	0.071 (8)	0.025 (7)	−0.007 (7)	−0.009 (6)
O7A	0.043 (7)	0.032 (3)	0.054 (3)	0.021 (5)	−0.002 (4)	−0.007 (2)
O8	0.0208 (19)	0.0208 (19)	0.027 (4)	0.0104 (10)	0.000	0.000
C1	0.0165 (13)	0.0207 (14)	0.0219 (14)	0.0098 (12)	0.0027 (11)	0.0045 (11)
C2	0.0159 (13)	0.0159 (13)	0.0201 (14)	0.0067 (11)	0.0002 (10)	0.0035 (10)
C3	0.0158 (14)	0.0155 (14)	0.0224 (14)	0.0052 (11)	0.0011 (11)	−0.0006 (11)
C4	0.0189 (13)	0.0148 (13)	0.0217 (15)	0.0101 (11)	0.0019 (11)	0.0009 (10)
C5	0.0239 (15)	0.0166 (13)	0.0224 (14)	0.0123 (12)	0.0030 (12)	0.0023 (11)
C6	0.0152 (13)	0.0183 (14)	0.0229 (15)	0.0081 (12)	0.0026 (11)	0.0006 (11)
C7	0.0189 (15)	0.0156 (14)	0.0179 (14)	0.0068 (12)	−0.0002 (11)	0.0004 (10)
C8	0.0165 (14)	0.0132 (13)	0.0247 (16)	0.0061 (12)	−0.0017 (11)	−0.0001 (11)
C9	0.0189 (14)	0.0134 (13)	0.0227 (14)	0.0072 (12)	0.0014 (11)	−0.0018 (11)

Geometric parameters (Å, º)

Ba1—O2^i	2.744 (2)	O7—H7A	0.85 (3)
Ba1—O2	2.744 (2)	O7—H7B	0.86 (3)
Ba1—O2^ii	2.744 (2)	O7A—H7AA	0.86 (3)
Ba1—O4^iii	2.779 (3)	O7A—H7AB	0.87 (3)
Ba1—O4^iv	2.779 (3)	O8—H8A^i	0.8500
Ba1—O4^v	2.779 (3)	O8—H8A^ii	0.8500
Ba1—O7^ii	2.969 (17)	O8—H8A	0.8500
Ba1—O7^i	2.969 (17)	O8—H8B^i	0.8500
Ba1—O7	2.969 (17)	O8—H8B	0.8500
Ba1—O7A^ii	2.966 (7)	O8—H8B^ii	0.8500
Ba1—O7A^i	2.966 (7)	C1—C2	1.495 (4)
Ba1—O7A	2.966 (7)	C2—C3	1.389 (4)
Zn1—O1	1.938 (2)	C2—C9	1.398 (4)
Zn1—O3^iv	1.944 (2)	C3—H3	0.9300
Zn1—O5^v	2.064 (2)	C3—C4	1.388 (4)
Zn1—O6^vi	2.082 (2)	C4—C5	1.507 (4)
O1—C1	1.282 (4)	C4—C6	1.391 (4)
O2—C1	1.227 (4)	C6—H6	0.9300
O3—C5	1.278 (4)	C6—C7	1.395 (4)
O4—C5	1.240 (4)	C7—C8	1.494 (4)
O5—C8	1.264 (4)	C7—C9	1.382 (4)
O6—C8	1.257 (4)	C9—H9	0.9300
O2^i—Ba1—O2	119.772 (12)	O1—Zn1—O5^v	103.68 (9)
O2^i—Ba1—O2^ii	119.771 (11)	O1—Zn1—O6^vi	97.62 (10)
O2—Ba1—O2^ii	119.770 (11)	O3^iv—Zn1—O5^v	89.88 (9)
O2^i—Ba1—O4^iii	75.99 (8)	O3^iv—Zn1—O6^vi	112.05 (10)
O2^ii—Ba1—O4^iv	75.99 (8)	O5^v—Zn1—O6^vi	94.02 (9)
O2^ii—Ba1—O4^iii	66.41 (8)	C1—O1—Zn1	117.7 (2)
O2—Ba1—O4^iii	137.97 (9)	C1—O2—Ba1	156.6 (2)
O2^i—Ba1—O4^v	66.41 (8)	C5—O3—Zn1^vii	115.9 (2)
O2—Ba1—O4^iv	66.41 (8)	C5—O4—Ba1^viii	136.2 (2)
O2—Ba1—O4^v	75.99 (8)	Zn1^ix—O5—Zn1^x	133.05 (11)
O2^ii—Ba1—O4^v	137.97 (9)	C8—O5—Zn1^ix	136.4 (2)
O2^i—Ba1—O4^iv	137.97 (9)	C8—O5—Zn1^x	82.97 (18)
O2^i—Ba1—O7^i	122.7 (10)	C8—O6—Zn1^x	100.0 (2)
O2^ii—Ba1—O7^ii	122.7 (10)	Ba1—O7—H7A	127 (7)
O2—Ba1—O7	122.7 (10)	Ba1—O7—H7B	125 (6)
O2^ii—Ba1—O7^i	83.7 (8)	H7A—O7—H7B	99 (7)
O2^i—Ba1—O7	83.7 (8)	Ba1—O7A—H7AA	118 (4)
O2^i—Ba1—O7^ii	57.2 (8)	Ba1—O7A—H7AB	117 (4)
O2^ii—Ba1—O7	57.2 (8)	H7AA—O7A—H7AB	94 (5)
O2—Ba1—O7^ii	83.7 (8)	H8A—O8—H8A^ii	107.3
O2—Ba1—O7^i	57.2 (8)	H8A^i—O8—H8A^ii	107.3
O2^i—Ba1—O7A	77.5 (5)	H8A—O8—H8A^i	107.3
O2^ii—Ba1—O7A^i	77.5 (5)	H8A—O8—H8B^ii	83.7
O2^i—Ba1—O7A^i	122.7 (4)	H8A—O8—H8B	104.5
O2—Ba1—O7A	122.7 (4)	H8A^i—O8—H8B^i	104.5
O2^i—Ba1—O7A^ii	63.9 (5)	H8A^i—O8—H8B^ii	26.4
O2^ii—Ba1—O7A	63.9 (5)	H8A—O8—H8B^i	26.4
O2—Ba1—O7A^ii	77.5 (5)	H8B—O8—H8A^i	83.7
O2^ii—Ba1—O7A^ii	122.7 (4)	H8B^ii—O8—H8A^ii	104.5
O2—Ba1—O7A^i	63.9 (5)	H8B^i—O8—H8A^ii	83.7
O4^v—Ba1—O4^iii	76.63 (9)	H8B—O8—H8A^ii	26.4
O4^v—Ba1—O4^iv	76.63 (9)	H8B—O8—H8B^i	78.1
O4^iii—Ba1—O4^iv	76.63 (9)	H8B—O8—H8B^ii	78.1
O4^v—Ba1—O7^ii	96.3 (10)	H8B^i—O8—H8B^ii	78.1
O4^iii—Ba1—O7^i	150.1 (8)	O1—C1—C2	115.8 (3)
O4^iii—Ba1—O7	96.3 (10)	O2—C1—O1	124.1 (3)
O4^iii—Ba1—O7^ii	130.6 (8)	O2—C1—C2	120.1 (3)
O4^v—Ba1—O7	150.1 (8)	C3—C2—C1	119.0 (3)
O4^iv—Ba1—O7^ii	150.1 (8)	C3—C2—C9	119.2 (3)
O4^iv—Ba1—O7	130.6 (8)	C9—C2—C1	121.7 (3)
O4^v—Ba1—O7^i	130.6 (8)	C2—C3—H3	119.7
O4^iv—Ba1—O7^i	96.3 (10)	C4—C3—C2	120.7 (3)
O4^iii—Ba1—O7A	98.0 (4)	C4—C3—H3	119.7
O4^iv—Ba1—O7A	137.7 (5)	C3—C4—C5	121.1 (3)
O4^iv—Ba1—O7A^i	98.0 (4)	C3—C4—C6	119.7 (3)
O4^iv—Ba1—O7A^ii	143.8 (5)	C6—C4—C5	119.1 (3)
O4^v—Ba1—O7A^ii	98.0 (4)	O3—C5—C4	117.2 (3)
O4^iii—Ba1—O7A^ii	137.7 (5)	O4—C5—O3	124.3 (3)
O4^v—Ba1—O7A^i	137.7 (5)	O4—C5—C4	118.4 (3)
O4^iii—Ba1—O7A^i	143.8 (5)	C4—C6—H6	120.1
O4^v—Ba1—O7A	143.8 (5)	C4—C6—C7	119.8 (3)
O7^ii—Ba1—O7	66.1 (16)	C7—C6—H6	120.1
O7^ii—Ba1—O7^i	66.1 (16)	C6—C7—C8	118.9 (3)
O7—Ba1—O7^i	66.1 (16)	C9—C7—C6	120.1 (3)
O7A^ii—Ba1—O7^ii	7.1 (7)	C9—C7—C8	121.0 (3)
O7A—Ba1—O7^ii	59.9 (8)	O5—C8—C7	120.3 (3)
O7A^i—Ba1—O7^ii	67.6 (6)	O6—C8—O5	120.0 (3)
O7A—Ba1—O7A^i	61.9 (7)	O6—C8—C7	119.7 (3)
O7A^ii—Ba1—O7A	61.9 (7)	C2—C9—H9	119.9
O7A^ii—Ba1—O7A^i	61.9 (7)	C7—C9—C2	120.3 (3)
O1—Zn1—O3^iv	146.48 (10)	C7—C9—H9	119.9
Ba1—O2—C1—O1	112.0 (5)	C1—C2—C9—C7	179.7 (3)
Ba1—O2—C1—C2	−66.8 (7)	C2—C3—C4—C5	−177.2 (3)
Ba1^viii—O4—C5—O3	−88.1 (4)	C2—C3—C4—C6	2.1 (4)
Ba1^viii—O4—C5—C4	94.3 (4)	C3—C2—C9—C7	−2.8 (4)
Zn1—O1—C1—O2	−9.0 (4)	C3—C4—C5—O3	−4.6 (4)
Zn1—O1—C1—C2	169.8 (2)	C3—C4—C5—O4	173.1 (3)
Zn1^vii—O3—C5—O4	−23.4 (4)	C3—C4—C6—C7	−2.9 (4)
Zn1^vii—O3—C5—C4	154.3 (2)	C4—C6—C7—C8	−178.3 (3)
Zn1^ix—O5—C8—O6	148.6 (3)	C4—C6—C7—C9	0.8 (5)
Zn1^x—O5—C8—O6	−1.5 (3)	C5—C4—C6—C7	176.4 (3)
Zn1^ix—O5—C8—C7	−33.0 (4)	C6—C4—C5—O3	176.0 (3)
Zn1^x—O5—C8—C7	176.8 (3)	C6—C4—C5—O4	−6.2 (4)
Zn1^x—O6—C8—O5	1.8 (3)	C6—C7—C8—O5	−40.2 (4)
Zn1^x—O6—C8—C7	−176.6 (2)	C6—C7—C8—O6	138.2 (3)
O1—C1—C2—C3	177.2 (3)	C6—C7—C9—C2	2.0 (5)
O1—C1—C2—C9	−5.3 (4)	C8—C7—C9—C2	−178.9 (3)
O2—C1—C2—C3	−3.9 (4)	C9—C2—C3—C4	0.7 (4)
O2—C1—C2—C9	173.6 (3)	C9—C7—C8—O5	140.8 (3)
C1—C2—C3—C4	178.3 (3)	C9—C7—C8—O6	−40.9 (4)

Symmetry codes: (i) −x+y, −x+1, z; (ii) −y+1, x−y+1, z; (iii) y, x+1, z−1/2; (iv) x−y+1, −y+1, z−1/2; (v) −x, −x+y, z−1/2; (vi) −x+y, −x, z; (vii) x−y, −y+1, z+1/2; (viii) y−1, x, z+1/2; (ix) −x, −x+y, z+1/2; (x) −y, x−y, z.