A third monoclinic polymorph of 3,4,5-trihy-droxy-benzoic acid monohydrate.

The title compound, C(7)H(6)O(5)·H(2)O, is a new polymorph of the structures reported by Jiang et al. (2000 ▶) [Acta Cryst. C56, 594-595] and Okabe et al. (2001 ▶) [Acta Cryst. E57, o764-o766]. The gallic acid mol-ecule is essentially planar (r.m.s. deviation = 0.550 Å). An intra-molecular O-H⋯O hydrogen bond occurs in the gallic acid mol-ecule, which is linked to the water mol-ecule by a further O-H⋯O hydrogen bond. In the crystal, the components are linked by O-H⋯O hydrogen bonds. The hydrogen-bonding pattern differs from those reported for the previous polymorphs.

Related literature

For the biological activity of gallic acid, see: Lu et al. (2006 ▶); Madlener et al. (2007 ▶). For the previously reproted polymorphs, see: Jiang et al. (2000 ▶); Okabe et al. (2001 ▶). For a related structure, see: Genç et al. (2004 ▶).

Experimental

Crystal data

C7H6O5·H2O

M = 188.13

Monoclinic,

a = 9.7943 (7) Å

b = 3.6122 (2) Å

c = 21.5905 (15) Å

β = 91.268 (6)°

V = 763.66 (9) Å3

Z = 4

Mo Kα radiation

μ = 0.15 mm−1

T = 296 K

0.61 × 0.28 × 0.09 mm

Data collection

Stoe IPDS 2 diffractometer

Absorption correction: integration (X-RED32; Stoe & Cie, 2002 ▶) T min = 0.948, T max = 0.986

4558 measured reflections

1502 independent reflections

1262 reflections with I > 2σ(I)

R int = 0.042

Refinement

R[F 2 > 2σ(F 2)] = 0.039

wR(F 2) = 0.104

S = 1.04

1502 reflections

127 parameters

3 restraints

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.15 e Å−3

Δρmin = −0.23 e Å−3

Data collection: X-AREA (Stoe & Cie, 2002 ▶); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002 ▶); program(s) used to solve structure: WinGX (Farrugia, 1997 ▶) and SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811018848/bx2352sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811018848/bx2352Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536811018848/bx2352Isup3.cml

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

C7H6O5·H2O	F(000) = 392
Mr = 188.13	Dx = 1.636 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 6472 reflections
a = 9.7943 (7) Å	θ = 1.9–27.6°
b = 3.6122 (2) Å	µ = 0.15 mm−1
c = 21.5905 (15) Å	T = 296 K
β = 91.268 (6)°	Needle, pale brown
V = 763.66 (9) Å3	0.61 × 0.28 × 0.09 mm
Z = 4

Stoe IPDS 2 diffractometer	1502 independent reflections
Radiation source: fine-focus sealed tube	1262 reflections with I > 2σ(I)
graphite	Rint = 0.042
w–scan rotation	θmax = 26.0°, θmin = 1.9°
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	h = −9→12
Tmin = 0.948, Tmax = 0.986	k = −4→4
4558 measured reflections	l = −26→26

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.039	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.104	w = 1/[σ2(Fo2) + (0.0466P)2 + 0.2493P] where P = (Fo2 + 2Fc2)/3
S = 1.04	(Δ/σ)max < 0.001
1502 reflections	Δρmax = 0.15 e Å−3
127 parameters	Δρmin = −0.23 e Å−3
3 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.023 (5)

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.

	x	y	z	Uiso*/Ueq
C1	0.67337 (16)	0.6332 (5)	0.58435 (8)	0.0369 (4)
H1	0.6383	0.7058	0.5459	0.044*
C2	0.81149 (16)	0.5670 (5)	0.59282 (8)	0.0349 (4)
C3	0.86369 (15)	0.4587 (5)	0.65029 (8)	0.0356 (4)
C4	0.77763 (17)	0.4238 (5)	0.70009 (8)	0.0395 (4)
C5	0.63957 (17)	0.4863 (5)	0.69214 (8)	0.0414 (4)
H5	0.5814	0.4596	0.7253	0.050*
C6	0.58767 (16)	0.5895 (5)	0.63421 (8)	0.0370 (4)
C7	0.43925 (16)	0.6603 (5)	0.62739 (8)	0.0408 (4)
O1	0.90229 (12)	0.5986 (4)	0.54561 (6)	0.0480 (4)
H2	0.8613	0.6599	0.5137	0.072*
O2	1.00108 (11)	0.3881 (4)	0.65588 (6)	0.0469 (4)
H3	1.0200	0.3265	0.6916	0.070*
O3	0.83973 (12)	0.3290 (5)	0.75521 (6)	0.0546 (4)
H4	0.7823	0.3169	0.7822	0.082*
O4	0.35878 (13)	0.5981 (5)	0.66792 (6)	0.0583 (4)
O5	0.40210 (12)	0.7959 (5)	0.57298 (6)	0.0567 (4)
H6	0.3193	0.8292	0.5719	0.085*
O6	0.14365 (13)	1.0125 (5)	0.56257 (7)	0.0499 (4)
H6A	0.120 (3)	1.147 (8)	0.5916 (12)	0.102 (11)*
H6B	0.077 (4)	0.879 (14)	0.555 (2)	0.24 (3)*

	U11	U22	U33	U12	U13	U23
C1	0.0338 (8)	0.0434 (9)	0.0333 (9)	0.0031 (7)	−0.0022 (7)	0.0016 (7)
C2	0.0310 (8)	0.0418 (9)	0.0321 (9)	0.0009 (7)	0.0036 (6)	0.0008 (7)
C3	0.0264 (7)	0.0457 (9)	0.0346 (9)	0.0013 (7)	−0.0009 (6)	−0.0010 (7)
C4	0.0337 (8)	0.0530 (11)	0.0316 (9)	0.0013 (7)	−0.0021 (6)	0.0037 (8)
C5	0.0322 (8)	0.0572 (11)	0.0349 (9)	0.0039 (7)	0.0042 (7)	0.0038 (8)
C6	0.0299 (8)	0.0444 (9)	0.0367 (9)	0.0041 (7)	0.0002 (7)	−0.0001 (7)
C7	0.0319 (8)	0.0525 (10)	0.0381 (10)	0.0049 (7)	0.0003 (7)	−0.0008 (8)
O1	0.0361 (6)	0.0738 (10)	0.0342 (7)	0.0052 (6)	0.0051 (5)	0.0085 (6)
O2	0.0286 (6)	0.0775 (10)	0.0345 (7)	0.0051 (6)	−0.0026 (5)	0.0035 (6)
O3	0.0334 (6)	0.0984 (12)	0.0321 (7)	0.0070 (7)	−0.0005 (5)	0.0138 (7)
O4	0.0335 (6)	0.0953 (12)	0.0465 (8)	0.0101 (7)	0.0074 (6)	0.0062 (8)
O5	0.0330 (6)	0.0882 (11)	0.0488 (8)	0.0137 (7)	−0.0020 (5)	0.0158 (7)
O6	0.0358 (7)	0.0697 (9)	0.0440 (8)	0.0126 (6)	−0.0016 (5)	0.0016 (7)

C1—C2	1.382 (2)	C5—H5	0.9300
C1—C6	1.388 (2)	C6—C7	1.480 (2)
C1—H1	0.9300	C7—O4	1.212 (2)
C2—O1	1.372 (2)	C7—O5	1.317 (2)
C2—C3	1.388 (2)	O1—H2	0.8200
C3—O2	1.3723 (19)	O2—H3	0.8200
C3—C4	1.387 (2)	O3—H4	0.8200
C4—O3	1.368 (2)	O5—H6	0.8200
C4—C5	1.378 (2)	O6—H6A	0.830 (18)
C5—C6	1.391 (2)	O6—H6B	0.824 (19)
C2—C1—C6	118.99 (15)	C4—C5—H5	120.2
C2—C1—H1	120.5	C6—C5—H5	120.2
C6—C1—H1	120.5	C1—C6—C5	120.83 (15)
O1—C2—C1	122.41 (14)	C1—C6—C7	120.83 (15)
O1—C2—C3	117.10 (14)	C5—C6—C7	118.32 (15)
C1—C2—C3	120.48 (15)	O4—C7—O5	122.82 (15)
O2—C3—C4	121.78 (14)	O4—C7—C6	123.32 (16)
O2—C3—C2	118.17 (14)	O5—C7—C6	113.86 (15)
C4—C3—C2	120.05 (14)	C2—O1—H2	109.5
O3—C4—C5	124.44 (16)	C3—O2—H3	109.5
O3—C4—C3	115.54 (14)	C4—O3—H4	109.5
C5—C4—C3	120.01 (15)	C7—O5—H6	109.5
C4—C5—C6	119.61 (16)	H6A—O6—H6B	105 (3)
C6—C1—C2—O1	178.97 (16)	O3—C4—C5—C6	178.56 (18)
C6—C1—C2—C3	0.0 (3)	C3—C4—C5—C6	−0.9 (3)
O1—C2—C3—O2	−0.5 (2)	C2—C1—C6—C5	1.0 (3)
C1—C2—C3—O2	178.51 (16)	C2—C1—C6—C7	179.51 (16)
O1—C2—C3—C4	179.56 (16)	C4—C5—C6—C1	−0.5 (3)
C1—C2—C3—C4	−1.4 (3)	C4—C5—C6—C7	−179.08 (17)
O2—C3—C4—O3	2.4 (3)	C1—C6—C7—O4	173.92 (19)
C2—C3—C4—O3	−177.66 (17)	C5—C6—C7—O4	−7.5 (3)
O2—C3—C4—C5	−178.04 (17)	C1—C6—C7—O5	−5.8 (3)
C2—C3—C4—C5	1.9 (3)	C5—C6—C7—O5	172.79 (18)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H3···O3	0.82	2.26	2.7006 (18)	114
O5—H6···O6	0.82	1.85	2.6542 (17)	167
O1—H2···O6i	0.82	2.03	2.7539 (19)	147
O2—H3···O3ii	0.82	2.52	3.1721 (19)	137
O3—H4···O4iii	0.82	1.94	2.7154 (19)	158
O6—H6A···O2iv	0.83 (2)	2.03 (2)	2.8237 (19)	161 (3)
O6—H6B···O1v	0.82 (2)	2.00 (2)	2.814 (2)	171 (5)

	1	2
Unit-cell parameters	a = 5.794 (4)	a = 14.15 (1)
	b = 4.719 (5)	b = 3.622 (9)
	c = 28.688 (5)	c = 15.028 (10)
	β = 95.08 (3)	β = 97.52 (7)
	V = 781.4 (3)	V = 764 (1)
Space group	Monoclinic, P21/c	Monoclinic, P2/n
Reference	Jiang et al. (2000)	Okabe et al. (2001)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H3⋯O3	0.82	2.26	2.7006 (18)	114
O5—H6⋯O6	0.82	1.85	2.6542 (17)	167
O1—H2⋯O6i	0.82	2.03	2.7539 (19)	147
O2—H3⋯O3ii	0.82	2.52	3.1721 (19)	137
O3—H4⋯O4iii	0.82	1.94	2.7154 (19)	158
O6—H6A⋯O2iv	0.83 (2)	2.03 (2)	2.8237 (19)	161 (3)
O6—H6B⋯O1v	0.82 (2)	2.00 (2)	2.814 (2)	171 (5)

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

Table 2

Other crystal structures of gallic acid monohydrate (Å, °)

	1	2
Unit-cell parameters	a = 5.794 (4)	a = 14.15 (1)
	b = 4.719 (5)	b = 3.622 (9)
	c = 28.688 (5)	c = 15.028 (10)
	β = 95.08 (3)	β = 97.52 (7)
	V = 781.4 (3)	V = 764 (1)
Space group	Monoclinic, P21/c	Monoclinic, P2/n
Reference	Jiang et al. (2000 ▶)	Okabe et al. (2001 ▶)