catena-Poly[[[tetra­aqua­zinc(II)]-μ-4,4′-bipyridine-κ2N:N′] benzene-1,4-di­carboxyl­ate]

Ruan, M.-B.; Deng, J.-C.; Li, Z.-G.; Xu, J.-W.

doi:10.1107/S1600536809019412

metal-organic compounds

CRYSTALLOGRAPHIC
COMMUNICATIONS

ISSN: 2056-9890

Volume 65| Part 7| July 2009| Page m743

doi:10.1107/S1600536809019412

Open

access

catena-Poly[[[tetraaquazinc(II)]-μ-4,4′-bipyridine-κ²N:N′] benzene-1,4-dicarboxylate]

Ming-Bo Ruan,^a Jian-Cheng Deng,^a ^* Zhi-Gang Li ^b and Jing-Wei Xu ^c

^aCollege of Chemistry, Xiangtan University, Hunan 411105, People's Republic of China, ^bNational Analytical Research Center of Electrochemistry and Spectroscopy, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China, and ^cState Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China
^*Correspondence e-mail: djcwye@163.com

(Received 30 April 2009; accepted 22 May 2009; online 6 June 2009)

In the title compound, {[Zn(C₁₀H₈N₂)(H₂O)₄](C₈H₄O₄)}_n, the Zn^II atoms, lying on a twofold rotation axis, are bridged by 4,4′-bipyridine ligands, resulting in a linear chain along the b axis. In the chain, the Zn^II atom adopts a slightly distorted octahedral coordination geometry involving four water molecules at the equatorial positions. The noncoordinated benzene-1,4-dicarboxylate anion, which is also located on a twofold rotation axis, bridges adjacent chains through O—H⋯O hydrogen bonds, forming a three-dimensional supramolecular network.

Related literature

For background information on hydrothermal reactions, see: Yaghi et al. (2003 ). For hydrogen-bond graph-set motifs, see: Bernstein et al. (1995 ).

Experimental

Crystal data

[Zn(C₁₀H₈N₂)(H₂O)₄](C₈H₄O₄)
M_r = 457.75
Monoclinic, P 2/n
a = 6.9861 (12) Å
b = 11.3436 (19) Å
c = 11.3219 (19) Å
β = 101.209 (3)°
V = 880.1 (3) Å³
Z = 2
Mo Kα radiation
μ = 1.45 mm⁻¹
T = 186 K
0.21 × 0.18 × 0.12 mm

Data collection

Bruker APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ) T_min = 0.751, T_max = 0.845
4812 measured reflections
1735 independent reflections
1465 reflections with I > 2σ(I)
R_int = 0.035

Refinement

R[F² > 2σ(F²)] = 0.042
wR(F²) = 0.108
S = 1.08
1735 reflections
136 parameters
H-atom parameters constrained
Δρ_max = 0.64 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1AA⋯O3ⁱ	0.87	1.89	2.753 (3)	169
O1—H1AB⋯O4ⁱⁱ	0.86	2.08	2.893 (3)	157
O2—H2AA⋯O4ⁱⁱⁱ	0.85	1.87	2.718 (3)	173
O2—H2AB⋯O3^iv	0.84	1.91	2.742 (3)	171
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+1, z-{\script{1\over 2}}]$ ; (ii) x+1, y+1, z; (iii) $[-x+{\script{3\over 2}}, y+1, -z+{\script{3\over 2}}]$ ; (iv) x+1, y, z.

Data collection: SMART (Bruker, 1998 ); cell refinement: SAINT-Plus (Bruker, 2003 ); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809019412/is2415sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536809019412/is2415Isup2.hkl

checkCIF report

Comment top

Hydro(solvo)thermal reaction has shown a kind of promising technique for the preparation of complexes with novel structures and special properties (Yaghi et al., 2003). Here we report the structure of the title compound, (I), which contains one-dimensional cation chains and non-coordinated benzene-1,4-dicarboxylate as couteranions under solvothermal condition.

Compound, (I), as shown in Fig. 1, consists of one-dimensional [Zn(C₁₀H₈N₂)(H₂O)₄]_n cation chains and benzene-1,4-dicarboxylate anions. The Zn(II) atoms are in a slightly distorted octahedral geometry, where two N atoms from two 4,4'-bipyridine ligands occupy the axial positions, and the equatorial positions are completed by four water molecules. The compound crystallizes in a centrosymmetric space group, which defines twofold axes along both the one-dimensional chains and the benzene-1,4-dicarboxylate anions.

In the crystal structure, intermolecular O—H···O hydrogen bonds are present (Table 1 and Fig. 2) and the coordinated water molecules are linked with two benzene-1,4-dicarboxylate anions to form R₄⁴(12) and R₆⁴(16) hydrogen-bonding rings (Bernstein et al., 1995). In addition, there are strong π···π interactions between pyridine rings and phenyl rings at (x, y, z) and (1/2 - x,1 + y, 3/2 - z), with the shortest atom-to-center distance of 3.322 (4) Å. The two kinds of interactions lead to a three-dimensional supramolecular network (Fig. 2).

Related literature top

For background information on hydrothermal reaction, see: Yaghi et al. (2003). For hydrogen-bond graph-set motifs, see: Bernstein et al. (1995).

Experimental top

Compound (I) was solvothermally prepared from a reaction mixture of Zn(BF₄)₂ (0.2 mmol), 4,4'-bipyridine (0.1 mmol), benzene-1,4-dicarboxylic acid (0.1 mmol), methanol (3 ml) and distilled water (8 ml) in a molar ratio of 2:1:740:4444; the pH value was adjusted to 4.8 with trimethylamine and acetic acid. The mixture was stirred for 20 min at room temperature and then sealed in a Teflon-lined stainless steel autoclave with a 23 ml capacity at 423 K for 72 h. After cooling to room temperature, colourless block-shaped crystals were obtained; these were washed with deionized water, filtered, and dried in air (yield 48% based on Zn).

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 2003); data reduction: SAINT-Plus (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top

	Fig. 1. The structure of (I), showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. View of the three-dimensional supramolecular structure in (I). Dashed lines indicate hydrogen bonds.

catena-Poly[[tetraaquazinc(II)]-µ-4,4'-bipyridine- κ²N:N'] benzene-1,4-dicarboxylate] top

Crystal data top

[Zn(C₁₀H₈N₂)(H₂O)₄](C₈H₄O₄)	F(000) = 472
M_r = 457.75	D_x = 1.727 Mg m⁻³
Monoclinic, P2/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yac	Cell parameters from 1213 reflections
a = 6.9861 (12) Å	θ = 2.3–24.8°
b = 11.3436 (19) Å	µ = 1.45 mm⁻¹
c = 11.3219 (19) Å	T = 186 K
β = 101.209 (3)°	Block, colorless
V = 880.1 (3) Å³	0.21 × 0.18 × 0.12 mm
Z = 2

Data collection top

Bruker APEX CCD area-detector diffractometer	1735 independent reflections
Radiation source: fine-focus sealed tube	1465 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.035
ϕ and ω scans	θ_max = 26.0°, θ_min = 1.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −8→4
T_min = 0.751, T_max = 0.845	k = −14→12
4812 measured reflections	l = −12→13

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.108	H-atom parameters constrained
S = 1.08	w = 1/[σ²(F_o²) + (0.0572P)² + 0.2035P] where P = (F_o² + 2F_c²)/3
1735 reflections	(Δ/σ)_max = 0.001
136 parameters	Δρ_max = 0.64 e Å⁻³
0 restraints	Δρ_min = −0.27 e Å⁻³

Crystal data top

[Zn(C₁₀H₈N₂)(H₂O)₄](C₈H₄O₄)	V = 880.1 (3) Å³
M_r = 457.75	Z = 2
Monoclinic, P2/n	Mo Kα radiation
a = 6.9861 (12) Å	µ = 1.45 mm⁻¹
b = 11.3436 (19) Å	T = 186 K
c = 11.3219 (19) Å	0.21 × 0.18 × 0.12 mm
β = 101.209 (3)°

Data collection top

Bruker APEX CCD area-detector diffractometer	1735 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	1465 reflections with I > 2σ(I)
T_min = 0.751, T_max = 0.845	R_int = 0.035
4812 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.042	0 restraints
wR(F²) = 0.108	H-atom parameters constrained
S = 1.08	Δρ_max = 0.64 e Å⁻³
1735 reflections	Δρ_min = −0.27 e Å⁻³
136 parameters

Special details top

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

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Zn1	0.7500	0.60167 (4)	0.7500	0.0231 (2)
N1	0.7500	0.7908 (3)	0.7500	0.0219 (8)
N2	0.7500	1.4169 (3)	0.7500	0.0233 (8)
O1	0.8792 (3)	0.61311 (19)	0.59227 (19)	0.0310 (6)
H1AA	0.8253	0.6201	0.5164	0.037*
H1AB	0.9941	0.6430	0.6054	0.037*
O2	1.0343 (3)	0.59315 (16)	0.8530 (2)	0.0272 (5)
H2AA	1.1223	0.6455	0.8544	0.033*
H2AB	1.1024	0.5339	0.8452	0.033*
O3	0.2410 (4)	0.38845 (18)	0.8474 (2)	0.0329 (6)
O4	0.2079 (3)	−0.22784 (18)	0.64951 (18)	0.0285 (5)
C1	0.8163 (4)	0.8531 (3)	0.8503 (3)	0.0231 (7)
H1A	0.8638	0.8121	0.9211	0.028*
C2	0.8179 (4)	0.9744 (3)	0.8544 (3)	0.0227 (7)
H2A	0.8642	1.0131	0.9267	0.027*
C3	0.7500	1.0391 (4)	0.7500	0.0192 (9)
C4	0.7500	1.1695 (3)	0.7500	0.0177 (9)
C5	0.7615 (5)	1.2339 (3)	0.8561 (3)	0.0223 (7)
H5	0.7694	1.1949	0.9292	0.027*
C6	0.7612 (5)	1.3551 (3)	0.8525 (3)	0.0255 (7)
H6	0.7691	1.3963	0.9243	0.031*
C7	0.2500	0.3377 (4)	0.7500	0.0245 (10)
C8	0.2500	0.2043 (4)	0.7500	0.0201 (9)
C9	0.1895 (4)	0.1414 (3)	0.6432 (3)	0.0225 (7)
H9	0.1501	0.1818	0.5711	0.027*
C10	0.1878 (4)	0.0195 (3)	0.6440 (3)	0.0225 (7)
H10	0.1442	−0.0210	0.5724	0.027*
C11	0.2500	−0.0438 (4)	0.7500	0.0200 (9)
C12	0.2500	−0.1761 (4)	0.7500	0.0244 (10)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn1	0.0313 (4)	0.0149 (3)	0.0225 (3)	0.000	0.0040 (2)	0.000
N1	0.027 (2)	0.0174 (18)	0.0222 (19)	0.000	0.0068 (15)	0.000
N2	0.028 (2)	0.0169 (18)	0.0242 (19)	0.000	0.0038 (16)	0.000
O1	0.0362 (14)	0.0349 (13)	0.0221 (12)	−0.0073 (10)	0.0066 (10)	−0.0017 (9)
O2	0.0287 (13)	0.0174 (11)	0.0339 (13)	−0.0010 (9)	0.0017 (10)	−0.0001 (9)
O3	0.0464 (16)	0.0256 (12)	0.0253 (13)	0.0101 (10)	0.0036 (11)	−0.0026 (9)
O4	0.0399 (14)	0.0217 (12)	0.0236 (12)	0.0017 (10)	0.0057 (10)	−0.0039 (9)
C1	0.0257 (18)	0.0225 (15)	0.0208 (15)	0.0014 (13)	0.0037 (13)	0.0027 (12)
C2	0.0265 (19)	0.0234 (16)	0.0179 (16)	−0.0005 (13)	0.0034 (13)	−0.0030 (12)
C3	0.018 (2)	0.019 (2)	0.023 (2)	0.000	0.0075 (18)	0.000
C4	0.012 (2)	0.018 (2)	0.023 (2)	0.000	0.0030 (17)	0.000
C5	0.0253 (17)	0.0227 (16)	0.0186 (15)	−0.0007 (13)	0.0032 (13)	0.0014 (12)
C6	0.033 (2)	0.0228 (15)	0.0202 (16)	−0.0001 (14)	0.0046 (14)	−0.0012 (12)
C7	0.025 (3)	0.022 (2)	0.024 (2)	0.000	−0.0009 (19)	0.000
C8	0.017 (2)	0.021 (2)	0.023 (2)	0.000	0.0079 (18)	0.000
C9	0.0266 (19)	0.0230 (15)	0.0181 (15)	0.0028 (13)	0.0047 (13)	0.0030 (12)
C10	0.0215 (18)	0.0267 (16)	0.0195 (16)	0.0009 (13)	0.0040 (13)	−0.0017 (12)
C11	0.018 (2)	0.020 (2)	0.023 (2)	0.000	0.0089 (18)	0.000
C12	0.023 (2)	0.022 (2)	0.029 (2)	0.000	0.006 (2)	0.000

Geometric parameters (Å, º) top

Zn1—N2ⁱ	2.096 (3)	C3—C2ⁱⁱ	1.394 (3)
Zn1—O2ⁱⁱ	2.101 (2)	C3—C4	1.479 (6)
Zn1—O2	2.101 (2)	C4—C5	1.395 (3)
Zn1—N1	2.145 (3)	C4—C5ⁱⁱ	1.395 (3)
Zn1—O1	2.156 (2)	C5—C6	1.376 (4)
Zn1—O1ⁱⁱ	2.156 (2)	C5—H5	0.9300
N1—C1	1.342 (3)	C6—H6	0.9300
N2—C6	1.344 (3)	C7—O3ⁱⁱⁱ	1.256 (3)
O1—H1AA	0.8719	C7—C8	1.513 (6)
O1—H1AB	0.8571	C8—C9	1.397 (3)
O2—H2AA	0.8525	C8—C9ⁱⁱⁱ	1.397 (3)
O2—H2AB	0.8379	C9—C10	1.383 (4)
O3—C7	1.256 (3)	C9—H9	0.9300
O4—C12	1.263 (3)	C10—C11	1.394 (3)
C1—C2	1.377 (4)	C10—H10	0.9300
C1—H1A	0.9300	C11—C10ⁱⁱⁱ	1.394 (4)
C2—C3	1.394 (3)	C11—C12	1.500 (6)
C2—H2A	0.9300	C12—O4ⁱⁱⁱ	1.263 (3)

N2ⁱ—Zn1—O2ⁱⁱ	87.36 (5)	C3—C2—H2A	120.0
N2ⁱ—Zn1—O2	87.36 (5)	C2ⁱⁱ—C3—C2	116.4 (4)
O2ⁱⁱ—Zn1—O2	174.73 (10)	C2ⁱⁱ—C3—C4	121.79 (19)
N2ⁱ—Zn1—N1	180.000 (1)	C2—C3—C4	121.79 (19)
O2ⁱⁱ—Zn1—N1	92.64 (5)	C5—C4—C5ⁱⁱ	116.8 (4)
O2—Zn1—N1	92.64 (5)	C5—C4—C3	121.58 (18)
N2ⁱ—Zn1—O1	93.45 (6)	C5ⁱⁱ—C4—C3	121.58 (18)
O2ⁱⁱ—Zn1—O1	92.63 (9)	C6—C5—C4	119.9 (3)
O2—Zn1—O1	87.69 (9)	C6—C5—H5	120.1
N1—Zn1—O1	86.55 (6)	C4—C5—H5	120.1
N2ⁱ—Zn1—O1ⁱⁱ	93.45 (6)	N2—C6—C5	123.1 (3)
O2ⁱⁱ—Zn1—O1ⁱⁱ	87.69 (9)	N2—C6—H6	118.4
O2—Zn1—O1ⁱⁱ	92.63 (9)	C5—C6—H6	118.4
N1—Zn1—O1ⁱⁱ	86.55 (6)	O3—C7—O3ⁱⁱⁱ	125.5 (4)
O1—Zn1—O1ⁱⁱ	173.10 (12)	O3—C7—C8	117.3 (2)
C1—N1—C1ⁱⁱ	116.4 (4)	O3ⁱⁱⁱ—C7—C8	117.3 (2)
C1—N1—Zn1	121.81 (18)	C9—C8—C9ⁱⁱⁱ	118.5 (4)
C1ⁱⁱ—N1—Zn1	121.81 (18)	C9—C8—C7	120.73 (19)
C6ⁱⁱ—N2—C6	117.2 (4)	C9ⁱⁱⁱ—C8—C7	120.73 (19)
C6ⁱⁱ—N2—Zn1^iv	121.42 (18)	C10—C9—C8	120.5 (3)
C6—N2—Zn1^iv	121.42 (18)	C10—C9—H9	119.8
Zn1—O1—H1AA	130.6	C8—C9—H9	119.8
Zn1—O1—H1AB	114.1	C9—C10—C11	121.3 (3)
H1AA—O1—H1AB	110.2	C9—C10—H10	119.4
Zn1—O2—H2AA	125.3	C11—C10—H10	119.4
Zn1—O2—H2AB	118.2	C10ⁱⁱⁱ—C11—C10	117.9 (4)
H2AA—O2—H2AB	98.0	C10ⁱⁱⁱ—C11—C12	121.03 (19)
N1—C1—C2	123.7 (3)	C10—C11—C12	121.03 (19)
N1—C1—H1A	118.2	O4—C12—O4ⁱⁱⁱ	124.6 (4)
C2—C1—H1A	118.2	O4—C12—C11	117.7 (2)
C1—C2—C3	119.9 (3)	O4ⁱⁱⁱ—C12—C11	117.7 (2)
C1—C2—H2A	120.0

Symmetry codes: (i) x, y−1, z; (ii) −x+3/2, y, −z+3/2; (iii) −x+1/2, y, −z+3/2; (iv) x, y+1, z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1AA···O3^v	0.87	1.89	2.753 (3)	169
O1—H1AB···O4^vi	0.86	2.08	2.893 (3)	157
O2—H2AA···O4^vii	0.85	1.87	2.718 (3)	173
O2—H2AB···O3^viii	0.84	1.91	2.742 (3)	171

Symmetry codes: (v) x+1/2, −y+1, z−1/2; (vi) x+1, y+1, z; (vii) −x+3/2, y+1, −z+3/2; (viii) x+1, y, z.

Experimental details

Crystal data
Chemical formula	[Zn(C₁₀H₈N₂)(H₂O)₄](C₈H₄O₄)
M_r	457.75
Crystal system, space group	Monoclinic, P2/n
Temperature (K)	186
a, b, c (Å)	6.9861 (12), 11.3436 (19), 11.3219 (19)
β (°)	101.209 (3)
V (Å³)	880.1 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	1.45
Crystal size (mm)	0.21 × 0.18 × 0.12

Data collection
Diffractometer	Bruker APEX CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.751, 0.845
No. of measured, independent and observed [I > 2σ(I)] reflections	4812, 1735, 1465
R_int	0.035
(sin θ/λ)_max (Å⁻¹)	0.617

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.042, 0.108, 1.08
No. of reflections	1735
No. of parameters	136
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.64, −0.27

Computer programs: SMART (Bruker, 1998), SAINT-Plus (Bruker, 2003), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1AA···O3ⁱ	0.87	1.89	2.753 (3)	169
O1—H1AB···O4ⁱⁱ	0.86	2.08	2.893 (3)	157
O2—H2AA···O4ⁱⁱⁱ	0.85	1.87	2.718 (3)	173
O2—H2AB···O3^iv	0.84	1.91	2.742 (3)	171

Symmetry codes: (i) x+1/2, −y+1, z−1/2; (ii) x+1, y+1, z; (iii) −x+3/2, y+1, −z+3/2; (iv) x+1, y, z.

Acknowledgements

This work was supported by the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, People's Republic of China.

References

Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573. CrossRef CAS Web of Science Google Scholar
Bruker (1998). SMART. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Bruker (2003). SAINT-Plus. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Yaghi, O. M., O'Keeffe, M., Ockwig, N. W., Chae, H. K., Eddaoudi, M. & Kim, J. (2003). Nature (London), 423, 705–714. Web of Science CrossRef PubMed CAS Google Scholar

This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.