2,3,4-Trihy-droxy-benzoic acid 0.25-hydrate.

The asymmetric unit of the title compound, C(7)H(6)O(5)·0.25H(2)O, contains two mol-ecules of 2,3,4-trihy-droxy-benzoic acid, with similar conformations, and one water mol-ecule which lies on a twofold rotation axis. Both acid mol-ecules are essentially planar [maximum r.m.s deviations = 0.0324 (2) and 0.0542 (3) Å for the two acid molecules]. The mol-ecular conformations are stabilized by intra-molecular O(phenol)-H⋯O(carbox-yl/phenol) inter-actions. A cyclic inter-molecular association is formed between the two acid and one water mol-ecule [graph set R(3) (3)(12)] involving O-H⋯O hydrogen bonds. The two acid mol-ecules are further linked through a cyclic R(2) (2)(8) carb-oxy-lic acid hydrogen-bonding association, which together with inter-molecular O-H⋯O hydrogen-bonding inter-actions involving the phenol groups and the water mol-ecule, and weak π-π inter-actions [minimum ring centroid separation = 3.731 (3) Å], give a three-dimensional network.

Related literature

For the natural distribution of 2,3,4-trihy­droxy­benzoic acid, see: Zhai et al. (2010 ▶); Xu & Chang (2010 ▶). For its anti­oxidant and anti­bacterial activities, see: Kodama et al. (2007 ▶); Friedman et al. (2003 ▶). For the inhibition of xanthine oxidase, see: Chang et al. (1995 ▶). For the crystal structure of the dihydrate pseudopolymorph, see: Prior & Sharp (2010 ▶). For π–π inter­actions in gallic acid pyridine monosolvate and in natural flavonoids, see: Dong et al. (2011 ▶); Jiang et al. (2009 ▶, 2002 ▶). For graph-set analysis, see: Etter et al. (1990 ▶); Bernstein et al. (1995 ▶).

Experimental

Crystal data

C7H6O5·0.25H2O

M = 174.62

Orthorhombic,

a = 11.8364 (12) Å

b = 32.598 (3) Å

c = 3.7306 (4) Å

V = 1439.4 (3) Å3

Z = 8

Mo Kα radiation

μ = 0.14 mm−1

T = 291 K

0.42 × 0.28 × 0.20 mm

Data collection

Bruker SMART 1000 CCD diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 2004 ▶) T min = 0.874, T max = 1.000

7863 measured reflections

2552 independent reflections

2010 reflections with I > 2σ(I)

R int = 0.060

Refinement

R[F 2 > 2σ(F 2)] = 0.036

wR(F 2) = 0.090

S = 0.97

2552 reflections

222 parameters

H-atom parameters constrained

Δρmax = 0.17 e Å−3

Δρmin = −0.15 e Å−3

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

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S160053681200709X/zs2181sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681200709X/zs2181Isup2.hkl

Supplementary material file. DOI: 10.1107/S160053681200709X/zs2181Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

C7H6O5·0.25H2O	F(000) = 724
Mr = 174.62	Dx = 1.612 Mg m−3
Orthorhombic, P21212	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2552 reflections
a = 11.8364 (12) Å	θ = 2.1–50.0°
b = 32.598 (3) Å	µ = 0.14 mm−1
c = 3.7306 (4) Å	T = 291 K
V = 1439.4 (3) Å3	Prism, light brown
Z = 8	0.42 × 0.28 × 0.20 mm

Bruker SMART 1000 CCD diffractometer	2552 independent reflections
Radiation source: fine-focus sealed tube	2010 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.060
ω scan	θmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −13→14
Tmin = 0.874, Tmax = 1.000	k = −38→34
7863 measured reflections	l = −4→4

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.090	H-atom parameters constrained
S = 0.97	w = 1/[σ2(Fo2) + (0.0443P)2] where P = (Fo2 + 2Fc2)/3
2552 reflections	(Δ/σ)max < 0.001
222 parameters	Δρmax = 0.17 e Å−3
0 restraints	Δρmin = −0.15 e Å−3

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. 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 > 2sigma(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.

	x	y	z	Uiso*/Ueq
O1W	0.5000	0.0000	−0.1102 (7)	0.0395 (6)
H1WA	0.5263	0.0173	0.0258	0.059*
O1	0.65345 (12)	0.12870 (4)	0.2193 (5)	0.0334 (4)
H1A	0.6637	0.1534	0.1900	0.040*
O2	0.65656 (13)	0.04688 (4)	0.3549 (4)	0.0323 (4)
H2A	0.6145	0.0640	0.4444	0.039*
O3	0.84576 (14)	0.00203 (5)	0.2010 (5)	0.0445 (5)
H3A	0.7859	−0.0048	0.2940	0.053*
O4	0.75826 (14)	0.19200 (4)	−0.0346 (6)	0.0429 (5)
O5	0.93058 (15)	0.18491 (4)	−0.2704 (6)	0.0481 (5)
H5B	0.9243	0.2098	−0.2919	0.058*
C1	0.84467 (19)	0.12653 (6)	−0.0250 (7)	0.0273 (5)
C2	0.74982 (19)	0.10787 (6)	0.1337 (6)	0.0245 (5)
C3	0.74932 (18)	0.06626 (6)	0.2074 (6)	0.0254 (5)
C4	0.84311 (19)	0.04271 (6)	0.1272 (7)	0.0295 (5)
C5	0.9374 (2)	0.06046 (7)	−0.0324 (7)	0.0330 (6)
H5A	0.9998	0.0444	−0.0891	0.040*
C6	0.9383 (2)	0.10180 (7)	−0.1064 (7)	0.0313 (6)
H6A	1.0018	0.1135	−0.2117	0.038*
C7	0.8406 (2)	0.17017 (7)	−0.1079 (7)	0.0310 (6)
O1'	0.49399 (13)	0.17376 (4)	−0.2824 (5)	0.0359 (4)
H1'A	0.4856	0.1982	−0.3270	0.043*
O2'	0.49999 (12)	0.09083 (4)	−0.2151 (5)	0.0308 (4)
H2'A	0.5380	0.1075	−0.1033	0.037*
O3'	0.32290 (14)	0.04439 (4)	−0.4474 (5)	0.0397 (5)
H3'A	0.3817	0.0378	−0.3464	0.048*
O4'	0.39072 (15)	0.23703 (5)	−0.5434 (6)	0.0446 (5)
O5'	0.22055 (15)	0.23003 (5)	−0.7935 (6)	0.0506 (5)
H5'B	0.2294	0.2547	−0.8259	0.061*
C1'	0.3088 (2)	0.17066 (7)	−0.5659 (7)	0.0293 (6)
C2'	0.40325 (19)	0.15242 (6)	−0.4052 (6)	0.0271 (6)
C3'	0.40863 (19)	0.11019 (6)	−0.3646 (6)	0.0267 (5)
C4'	0.31874 (19)	0.08593 (6)	−0.4795 (7)	0.0281 (6)
C5'	0.22322 (19)	0.10389 (7)	−0.6322 (7)	0.0328 (6)
H5'A	0.1630	0.0876	−0.7056	0.039*
C6'	0.2185 (2)	0.14569 (7)	−0.6737 (7)	0.0336 (6)
H6'A	0.1546	0.1576	−0.7746	0.040*
C7'	0.3098 (2)	0.21492 (7)	−0.6310 (7)	0.0349 (6)

	U11	U22	U33	U12	U13	U23
O1W	0.0469 (15)	0.0229 (11)	0.0486 (16)	−0.0056 (10)	0.000	0.000
O1	0.0299 (9)	0.0177 (7)	0.0527 (11)	0.0023 (6)	0.0057 (9)	0.0020 (8)
O2	0.0280 (9)	0.0212 (8)	0.0475 (11)	0.0003 (6)	0.0064 (8)	0.0020 (8)
O3	0.0386 (10)	0.0215 (8)	0.0734 (13)	0.0038 (7)	0.0121 (10)	0.0077 (10)
O4	0.0398 (11)	0.0244 (8)	0.0644 (13)	−0.0006 (8)	0.0084 (10)	0.0075 (9)
O5	0.0463 (11)	0.0268 (9)	0.0713 (14)	−0.0031 (8)	0.0157 (11)	0.0094 (10)
C1	0.0298 (13)	0.0244 (11)	0.0278 (13)	−0.0029 (10)	−0.0040 (11)	0.0009 (11)
C2	0.0265 (12)	0.0208 (11)	0.0261 (13)	0.0014 (9)	−0.0058 (11)	−0.0024 (10)
C3	0.0285 (13)	0.0211 (11)	0.0268 (12)	−0.0056 (9)	−0.0017 (11)	0.0004 (10)
C4	0.0334 (14)	0.0193 (11)	0.0359 (14)	0.0014 (10)	−0.0033 (12)	0.0009 (11)
C5	0.0278 (14)	0.0303 (13)	0.0409 (15)	0.0041 (10)	0.0006 (12)	−0.0034 (12)
C6	0.0257 (13)	0.0324 (13)	0.0360 (15)	−0.0042 (10)	−0.0001 (12)	0.0006 (11)
C7	0.0315 (14)	0.0255 (12)	0.0361 (14)	−0.0068 (11)	−0.0040 (12)	0.0019 (11)
O1'	0.0346 (9)	0.0185 (7)	0.0546 (11)	−0.0032 (6)	−0.0058 (10)	0.0011 (8)
O2'	0.0294 (9)	0.0191 (7)	0.0440 (10)	0.0016 (6)	−0.0038 (9)	0.0011 (7)
O3'	0.0408 (11)	0.0207 (8)	0.0575 (12)	−0.0029 (7)	−0.0115 (9)	−0.0004 (9)
O4'	0.0476 (12)	0.0208 (8)	0.0655 (14)	0.0004 (8)	−0.0142 (10)	0.0057 (9)
O5'	0.0482 (11)	0.0279 (9)	0.0758 (14)	0.0047 (8)	−0.0172 (12)	0.0138 (10)
C1'	0.0340 (14)	0.0227 (12)	0.0312 (13)	0.0031 (10)	0.0040 (11)	−0.0003 (11)
C2'	0.0295 (13)	0.0221 (12)	0.0297 (14)	−0.0024 (10)	0.0035 (12)	−0.0021 (10)
C3'	0.0280 (13)	0.0231 (11)	0.0290 (13)	0.0037 (10)	0.0045 (11)	0.0009 (10)
C4'	0.0334 (14)	0.0199 (11)	0.0311 (14)	0.0005 (10)	0.0052 (11)	−0.0007 (11)
C5'	0.0297 (14)	0.0299 (12)	0.0388 (15)	−0.0033 (10)	−0.0005 (12)	−0.0019 (12)
C6'	0.0342 (14)	0.0326 (12)	0.0339 (15)	0.0051 (10)	−0.0039 (12)	0.0022 (12)
C7'	0.0399 (16)	0.0271 (13)	0.0376 (15)	0.0071 (11)	0.0020 (12)	0.0021 (12)

O1W—H1WA	0.8200	O1'—C2'	1.359 (3)
O1—C2	1.365 (3)	O1'—H1'A	0.8200
O1—H1A	0.8200	O2'—C3'	1.371 (3)
O2—C3	1.381 (3)	O2'—H2'A	0.8200
O2—H2A	0.8200	O3'—C4'	1.360 (2)
O3—C4	1.355 (2)	O3'—H3'A	0.8200
O3—H3A	0.8200	O4'—C7'	1.243 (3)
O4—C7	1.237 (3)	O5'—C7'	1.314 (3)
O5—C7	1.317 (3)	O5'—H5'B	0.8200
O5—H5B	0.8200	C1'—C2'	1.401 (3)
C1—C6	1.404 (3)	C1'—C6'	1.403 (3)
C1—C2	1.407 (3)	C1'—C7'	1.463 (3)
C1—C7	1.457 (3)	C2'—C3'	1.386 (3)
C2—C3	1.384 (3)	C3'—C4'	1.393 (3)
C3—C4	1.382 (3)	C4'—C5'	1.395 (3)
C4—C5	1.391 (3)	C5'—C6'	1.373 (3)
C5—C6	1.376 (3)	C5'—H5'A	0.9300
C5—H5A	0.9300	C6'—H6'A	0.9300
C6—H6A	0.9300
C2—O1—H1A	109.5	C2'—O1'—H1'A	109.5
C3—O2—H2A	109.5	C3'—O2'—H2'A	109.5
C4—O3—H3A	109.5	C4'—O3'—H3'A	109.5
C7—O5—H5B	109.5	C7'—O5'—H5'B	109.5
C6—C1—C2	118.2 (2)	C2'—C1'—C6'	119.0 (2)
C6—C1—C7	122.8 (2)	C2'—C1'—C7'	118.9 (2)
C2—C1—C7	119.0 (2)	C6'—C1'—C7'	122.1 (2)
O1—C2—C3	115.9 (2)	O1'—C2'—C3'	115.8 (2)
O1—C2—C1	123.35 (18)	O1'—C2'—C1'	123.89 (18)
C3—C2—C1	120.7 (2)	C3'—C2'—C1'	120.3 (2)
O2—C3—C4	118.08 (17)	O2'—C3'—C2'	122.5 (2)
O2—C3—C2	122.06 (19)	O2'—C3'—C4'	117.79 (18)
C4—C3—C2	119.9 (2)	C2'—C3'—C4'	119.7 (2)
O3—C4—C3	121.2 (2)	O3'—C4'—C3'	120.7 (2)
O3—C4—C5	118.4 (2)	O3'—C4'—C5'	118.9 (2)
C3—C4—C5	120.4 (2)	C3'—C4'—C5'	120.4 (2)
C6—C5—C4	119.9 (2)	C6'—C5'—C4'	119.7 (2)
C6—C5—H5A	120.0	C6'—C5'—H5'A	120.1
C4—C5—H5A	120.0	C4'—C5'—H5'A	120.1
C5—C6—C1	120.9 (2)	C5'—C6'—C1'	120.8 (2)
C5—C6—H6A	119.6	C5'—C6'—H6'A	119.6
C1—C6—H6A	119.6	C1'—C6'—H6'A	119.6
O4—C7—O5	122.0 (2)	O4'—C7'—O5'	121.6 (2)
O4—C7—C1	122.7 (2)	O4'—C7'—C1'	122.3 (2)
O5—C7—C1	115.3 (2)	O5'—C7'—C1'	116.1 (2)
C6—C1—C2—O1	−178.9 (2)	C6'—C1'—C2'—O1'	−178.2 (2)
C7—C1—C2—O1	−0.8 (3)	C7'—C1'—C2'—O1'	4.6 (4)
C6—C1—C2—C3	0.1 (3)	C6'—C1'—C2'—C3'	2.1 (4)
C7—C1—C2—C3	178.2 (2)	C7'—C1'—C2'—C3'	−175.1 (2)
O1—C2—C3—O2	0.7 (3)	O1'—C2'—C3'—O2'	−0.9 (3)
C1—C2—C3—O2	−178.4 (2)	C1'—C2'—C3'—O2'	178.8 (2)
O1—C2—C3—C4	179.6 (2)	O1'—C2'—C3'—C4'	179.3 (2)
C1—C2—C3—C4	0.5 (3)	C1'—C2'—C3'—C4'	−1.0 (4)
O2—C3—C4—O3	−2.0 (3)	O2'—C3'—C4'—O3'	−0.8 (3)
C2—C3—C4—O3	179.0 (2)	C2'—C3'—C4'—O3'	179.0 (2)
O2—C3—C4—C5	177.9 (2)	O2'—C3'—C4'—C5'	179.7 (2)
C2—C3—C4—C5	−1.0 (4)	C2'—C3'—C4'—C5'	−0.5 (4)
O3—C4—C5—C6	−179.1 (2)	O3'—C4'—C5'—C6'	−178.6 (2)
C3—C4—C5—C6	1.0 (4)	C3'—C4'—C5'—C6'	0.9 (4)
C4—C5—C6—C1	−0.4 (4)	C4'—C5'—C6'—C1'	0.3 (4)
C2—C1—C6—C5	−0.1 (4)	C2'—C1'—C6'—C5'	−1.8 (4)
C7—C1—C6—C5	−178.2 (2)	C7'—C1'—C6'—C5'	175.3 (2)
C6—C1—C7—O4	−179.6 (2)	C2'—C1'—C7'—O4'	−1.2 (4)
C2—C1—C7—O4	2.3 (4)	C6'—C1'—C7'—O4'	−178.3 (2)
C6—C1—C7—O5	1.0 (3)	C2'—C1'—C7'—O5'	177.7 (2)
C2—C1—C7—O5	−177.1 (2)	C6'—C1'—C7'—O5'	0.6 (4)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O2	0.82	2.19	2.963 (2)	156
O1W—H1WA···O2′	0.82	2.58	2.987 (3)	112
O1—H1A···O4	0.82	1.88	2.587 (3)	143
O2—H2A···O2′i	0.82	2.05	2.839 (4)	161
O2—H2A···O1	0.82	2.32	2.715 (2)	111
O3—H3A···O3′ii	0.82	2.06	2.828 (3)	155
O3—H3A···O2	0.82	2.29	2.735 (3)	115
O5—H5B···O4′iii	0.82	1.88	2.679 (4)	165
O1′—H1′A···O4′	0.82	1.87	2.588 (3)	145
O2′—H2′A···O1	0.82	1.95	2.729 (4)	159
O2′—H2′A···O1′	0.82	2.32	2.716 (2)	110
O3′—H3′A···O1W	0.82	2.06	2.841 (3)	158
O3′—H3′A···O2′	0.82	2.28	2.727 (4)	115
O5′—H5′B···O4iv	0.82	1.85	2.659 (4)	171

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H1WA⋯O2	0.82	2.19	2.963 (2)	156
O1—H1A⋯O4	0.82	1.88	2.587 (3)	143
O2—H2A⋯O2′i	0.82	2.05	2.839 (4)	161
O3—H3A⋯O3′ii	0.82	2.06	2.828 (3)	155
O5—H5B⋯O4′iii	0.82	1.88	2.679 (4)	165
O1′—H1′A⋯O4′	0.82	1.87	2.588 (3)	145
O2′—H2′A⋯O1	0.82	1.95	2.729 (4)	159
O3′—H3′A⋯O1W	0.82	2.06	2.841 (3)	158
O5′—H5′B⋯O4iv	0.82	1.85	2.659 (4)	171

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .