A triclinic modification of 3,4-dihy­droxy­benzoic acid monohydrate

Ng, S.W.

doi:10.1107/S1600536811034635

organic compounds

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ISSN: 2056-9890

Volume 67| Part 9| September 2011| Page o2476

doi:10.1107/S1600536811034635

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A triclinic modification of 3,4-dihydroxybenzoic acid monohydrate

Seik Weng Ng ^a ^*

^aDepartment of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia, and Chemistry Department, Faculty of Science, King Abdulaziz University, PO Box 80203 Jeddah, Saudi Arabia
^*Correspondence e-mail: seikweng@um.edu.my

(Received 22 August 2011; accepted 23 August 2011; online 27 August 2011)

The unit cell of the title compound, C₇H₆O₄·H₂O, features four independent formula units; the individual carboxylic acid molecules themselves are nearly planar (r.m.s. deviations = 0.0189, 0.0334, 0.0356 and 0.0441 Å). Two independent molecules each form two hydrogen bonds by acid–carbonyl O—H⋯O interactions and the dimers are also nearly planar (r.m.s. deviations = 0.039 and 0.049 Å). The two independent dimers are aligned at 44.5 (1)°. Other O—H⋯O interactions involving the hydroxy groups and water molecules give rise to a three-dimensional network.

Related literature

For the triclinic modification whose cell is about half the volume of the present triclinic modification, see: Horneffer et al. (1999 ).

Experimental

Crystal data

C₇H₆O₄·H₂O
M_r = 172.13
Triclinic, $[P \overline 1]$
a = 7.1105 (3) Å
b = 12.7807 (5) Å
c = 17.5318 (7) Å
α = 72.491 (4)°
β = 89.901 (3)°
γ = 74.457 (3)°
V = 1458.45 (10) Å³
Z = 8
Cu Kα radiation
μ = 1.18 mm⁻¹
T = 100 K
0.20 × 0.10 × 0.10 mm

Data collection

Agilent Technologies SuperNova Dual diffractometer with Atlas detector
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010 ) T_min = 0.798, T_max = 0.891
9167 measured reflections
5301 independent reflections
4910 reflections with I > 2σ(I)
R_int = 0.020

Refinement

R[F² > 2σ(F²)] = 0.056
wR(F²) = 0.161
S = 1.15
5301 reflections
513 parameters
24 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.35 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O6	0.85 (1)	1.83 (1)	2.678 (3)	178 (3)
O3—H3⋯O1Wⁱ	0.84 (1)	1.99 (1)	2.803 (3)	163 (3)
O4—H4⋯O4Wⁱⁱ	0.84 (1)	1.86 (2)	2.674 (3)	163 (4)
O5—H5⋯O2	0.85 (1)	1.76 (1)	2.593 (3)	170 (4)
O7—H7⋯O3ⁱⁱⁱ	0.84 (1)	1.91 (1)	2.746 (3)	172 (4)
O8—H8⋯O3W^iv	0.84 (1)	1.94 (1)	2.772 (3)	171 (4)
O9—H9⋯O14	0.84 (1)	1.84 (2)	2.664 (3)	166 (5)
O11—H11⋯O3W^v	0.84 (1)	2.02 (2)	2.824 (3)	161 (4)
O12—H12⋯O1W	0.84 (1)	1.92 (1)	2.760 (3)	175 (4)
O13—H13⋯O10	0.84 (1)	1.76 (1)	2.599 (3)	171 (5)
O15—H15⋯O11^vi	0.84 (1)	1.91 (1)	2.754 (2)	178 (4)
O16—H16⋯O2W^vii	0.84 (1)	1.92 (2)	2.699 (3)	153 (4)
O1W—H1W1⋯O2	0.84 (1)	2.36 (5)	2.920 (3)	124 (4)
O1W—H1W2⋯O2W^viii	0.84 (1)	2.07 (1)	2.911 (4)	173 (7)
O2W—H2W1⋯O6	0.85 (1)	2.24 (1)	3.071 (3)	168 (4)
O2W—H2W2⋯O7^ix	0.85 (1)	2.00 (2)	2.823 (3)	165 (4)
O3W—H3W1⋯O10	0.85 (1)	2.40 (4)	2.933 (3)	122 (3)
O3W—H3W2⋯O4W^x	0.84 (1)	2.08 (1)	2.920 (4)	174 (6)
O4W—H4W1⋯O14	0.85 (1)	2.30 (3)	3.079 (3)	152 (5)
O4W—H4W2⋯O15^xi	0.86 (1)	1.97 (1)	2.806 (3)	164 (4)
Symmetry codes: (i) -x+3, -y, -z+1; (ii) -x+2, -y+1, -z+1; (iii) x-1, y+1, z; (iv) -x+2, -y+2, -z; (v) -x+2, -y+1, -z; (vi) x, y+1, z; (vii) x-1, y+1, z-1; (viii) -x+3, -y+1, -z+1; (ix) -x+2, -y+2, -z+1; (x) -x+1, -y+2, -z; (xi) -x+1, -y+3, -z.

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001 ); software used to prepare material for publication: publCIF (Westrip, 2010 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811034635/xu5306sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811034635/xu5306Isup2.hkl

Supporting information file. DOI: 10.1107/S1600536811034635/xu5306Isup3.cml

checkCIF report

Comment top

3,4-Dihydroxybenzoic acid monohydrate (Scheme I) was reported as a triclinic crystal [a 8.045, b 8.134, c 12.692 Å; α 71.58, β 76.79, γ 72.17 °]; there are two independent formula units in the unit cell (Horneffer et al., 1999). The carboxylic acid is a commerically available compound. This carboxylic acid when isolated from a plant crystallizes as a monohydrate and its unit cell is twice as large so that there are four independent molecules (Fig. 1). The individual carboxylic acid molecules themselves are planar. Two independent molecules form two hydrogen bonds by O–H_acid···O_carbonyl interactions. Other O–H···O interactions that involve the hydroxy groups and water molecules give rise to a three-dimensional network (Table 1).

Related literature top

For the triclinic modification whose cell is half the volume of the present triclinic modification, see: Horneffer et al. (1999).

Experimental top

The aerial part of Dodonaea viscosa (20 kg) was powdered and extracted with methanol (10 L x 3) at room temperature and the crude residue (2 kg) was obtained after removal of methanol under reduced pressure. The residue was suspended in water and extracted with n-hexane,chloroform, ethyl acetate and n-butanol. The ethyl acetate fraction (250 g) was subjected repeatedly to column chromatography on silica gel. The compound (10 mg) was found in a polarity range 50% ethyl acetate to 50% ethyl acetate:n-hexane. Crystals of 3,4-dihydroxybenzoic acid monohydrate were the unexpected compound that were obtained by recrystallization from a 1:1 acetone:n-hexane mixture.

Computing details top

Data collection: CrysAlis PRO (Agilent, 2010); cell refinement: CrysAlis PRO (Agilent, 2010); data reduction: CrysAlis PRO (Agilent, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: X-SEED (Barbour, 2001); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top

Fig. 1. Thermal ellipsoid plot (Barbour, 2001) of the four independent formula units molecules of C₇H₆O₄^.H₂O at the 70% probability level; hydrogen atoms are drawn as spheres of arbitrary radius.

3,4-dihydroxybenzoic acid monohydrate top

Crystal data top

C₇H₆O₄·H₂O	Z = 8
M_r = 172.13	F(000) = 720
Triclinic, P1	D_x = 1.568 Mg m⁻³
Hall symbol: -P 1	Cu Kα radiation, λ = 1.54184 Å
a = 7.1105 (3) Å	Cell parameters from 5539 reflections
b = 12.7807 (5) Å	θ = 2.7–74.2°
c = 17.5318 (7) Å	µ = 1.18 mm⁻¹
α = 72.491 (4)°	T = 100 K
β = 89.901 (3)°	Block, colorless
γ = 74.457 (3)°	0.20 × 0.10 × 0.10 mm
V = 1458.45 (10) Å³

Data collection top

Agilent Technologies SuperNova Dual diffractometer with Atlas detector	5301 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	4910 reflections with I > 2σ(I)
Mirror monochromator	R_int = 0.020
Detector resolution: 10.4041 pixels mm^-1	θ_max = 70.0°, θ_min = 2.7°
ω scan	h = −8→8
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	k = −12→15
T_min = 0.798, T_max = 0.891	l = −19→21
9167 measured reflections

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)] = 0.056	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.161	H atoms treated by a mixture of independent and constrained refinement
S = 1.15	w = 1/[σ²(F_o²) + (0.0556P)² + 2.5625P] where P = (F_o² + 2F_c²)/3
5301 reflections	(Δ/σ)_max = 0.001
513 parameters	Δρ_max = 0.31 e Å⁻³
24 restraints	Δρ_min = −0.35 e Å⁻³

Crystal data top

C₇H₆O₄·H₂O	γ = 74.457 (3)°
M_r = 172.13	V = 1458.45 (10) Å³
Triclinic, P1	Z = 8
a = 7.1105 (3) Å	Cu Kα radiation
b = 12.7807 (5) Å	µ = 1.18 mm⁻¹
c = 17.5318 (7) Å	T = 100 K
α = 72.491 (4)°	0.20 × 0.10 × 0.10 mm
β = 89.901 (3)°

Data collection top

Agilent Technologies SuperNova Dual diffractometer with Atlas detector	5301 independent reflections
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2010)	4910 reflections with I > 2σ(I)
T_min = 0.798, T_max = 0.891	R_int = 0.020
9167 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.056	24 restraints
wR(F²) = 0.161	H atoms treated by a mixture of independent and constrained refinement
S = 1.15	Δρ_max = 0.31 e Å⁻³
5301 reflections	Δρ_min = −0.35 e Å⁻³
513 parameters

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

	x	y	z	U_iso*/U_eq
O1	1.2471 (3)	0.40038 (16)	0.61115 (12)	0.0256 (4)
O2	1.3653 (3)	0.37601 (17)	0.49778 (12)	0.0300 (5)
O3	1.6748 (3)	−0.04656 (15)	0.56841 (10)	0.0180 (4)
O4	1.5861 (3)	−0.13742 (16)	0.71721 (11)	0.0252 (4)
O5	1.2564 (3)	0.58919 (16)	0.41063 (12)	0.0251 (4)
O6	1.1385 (3)	0.62121 (16)	0.52267 (12)	0.0284 (5)
O7	0.8230 (3)	1.05257 (15)	0.42888 (11)	0.0195 (4)
O8	0.9107 (3)	1.12551 (16)	0.28104 (11)	0.0248 (4)
O9	0.8607 (3)	0.89145 (17)	0.11507 (12)	0.0253 (4)
O10	0.7645 (3)	0.86456 (16)	0.00291 (12)	0.0284 (5)
O11	0.8783 (3)	0.44030 (15)	0.07687 (10)	0.0187 (4)
O12	1.0448 (3)	0.35333 (16)	0.22821 (11)	0.0236 (4)
O13	0.6605 (3)	1.07815 (17)	−0.08454 (12)	0.0249 (4)
O14	0.7424 (3)	1.11112 (16)	0.02742 (12)	0.0289 (5)
O15	0.6378 (3)	1.54151 (15)	−0.06371 (10)	0.0189 (4)
O16	0.4748 (3)	1.61621 (16)	−0.21018 (11)	0.0249 (4)
O1w	1.2446 (4)	0.28526 (18)	0.37766 (13)	0.0341 (5)
O2w	1.3495 (4)	0.70908 (18)	0.63249 (12)	0.0331 (5)
O3w	0.9674 (4)	0.79992 (18)	−0.12887 (12)	0.0338 (5)
O4w	0.4321 (4)	1.22050 (17)	0.12445 (12)	0.0330 (5)
C1	1.3388 (4)	0.3346 (2)	0.56934 (16)	0.0203 (5)
C2	1.4042 (4)	0.2126 (2)	0.61156 (15)	0.0177 (5)
C3	1.5080 (3)	0.1395 (2)	0.57062 (15)	0.0165 (5)
H3A	1.5360	0.1702	0.5168	0.020*
C4	1.5690 (3)	0.0240 (2)	0.60809 (15)	0.0157 (5)
C5	1.5253 (4)	−0.0231 (2)	0.68730 (15)	0.0176 (5)
C6	1.4231 (4)	0.0501 (2)	0.72805 (15)	0.0195 (5)
H6	1.3942	0.0193	0.7817	0.023*
C7	1.3637 (4)	0.1667 (2)	0.69096 (15)	0.0190 (5)
H7A	1.2953	0.2159	0.7193	0.023*
C8	1.1644 (4)	0.6581 (2)	0.45019 (16)	0.0205 (5)
C9	1.0988 (4)	0.7786 (2)	0.40319 (15)	0.0180 (5)
C10	0.9914 (4)	0.8576 (2)	0.43934 (15)	0.0168 (5)
H10	0.9615	0.8316	0.4934	0.020*
C11	0.9296 (4)	0.9715 (2)	0.39720 (15)	0.0169 (5)
C12	0.9758 (4)	1.0115 (2)	0.31738 (15)	0.0183 (5)
C13	1.0818 (4)	0.9330 (2)	0.28172 (15)	0.0195 (5)
H13A	1.1135	0.9590	0.2279	0.023*
C14	1.1415 (4)	0.8177 (2)	0.32373 (15)	0.0185 (5)
H14	1.2118	0.7648	0.2984	0.022*
C15	0.8338 (4)	0.8252 (2)	0.07383 (16)	0.0204 (5)
C16	0.8902 (4)	0.7023 (2)	0.11704 (15)	0.0180 (5)
C17	0.8602 (3)	0.6279 (2)	0.07704 (15)	0.0163 (5)
H17A	0.8046	0.6572	0.0230	0.020*
C18	0.9116 (4)	0.5119 (2)	0.11619 (15)	0.0165 (5)
C19	0.9973 (4)	0.4682 (2)	0.19596 (15)	0.0179 (5)
C20	1.0265 (4)	0.5431 (2)	0.23495 (15)	0.0198 (5)
H20	1.0834	0.5141	0.2888	0.024*
C21	0.9735 (4)	0.6593 (2)	0.19609 (16)	0.0190 (5)
H21	0.9939	0.7100	0.2232	0.023*
C22	0.6821 (4)	1.1473 (2)	−0.04506 (16)	0.0213 (6)
C23	0.6298 (4)	1.2688 (2)	−0.09188 (15)	0.0181 (5)
C24	0.6587 (4)	1.3467 (2)	−0.05472 (15)	0.0170 (5)
H24A	0.7125	1.3200	−0.0005	0.020*
C25	0.6095 (4)	1.4616 (2)	−0.09623 (15)	0.0166 (5)
C26	0.5238 (4)	1.5018 (2)	−0.17551 (15)	0.0172 (5)
C27	0.4966 (4)	1.4243 (2)	−0.21265 (15)	0.0196 (5)
H27	0.4411	1.4510	−0.2666	0.023*
C28	0.5500 (4)	1.3081 (2)	−0.17132 (16)	0.0191 (5)
H28	0.5322	1.2554	−0.1971	0.023*
H1	1.212 (5)	0.4696 (12)	0.5821 (17)	0.030 (9)*
H3	1.694 (5)	−0.1161 (11)	0.5938 (18)	0.031 (9)*
H4	1.557 (6)	−0.162 (3)	0.7646 (10)	0.051 (12)*
H5	1.289 (5)	0.5224 (15)	0.4440 (17)	0.039 (10)*
H7	0.781 (6)	1.016 (3)	0.4706 (16)	0.065 (14)*
H8	0.942 (6)	1.143 (4)	0.2336 (11)	0.062 (13)*
H9	0.811 (7)	0.9575 (19)	0.083 (2)	0.078 (16)*
H11	0.916 (5)	0.3703 (11)	0.1026 (19)	0.038 (10)*
H12	1.100 (5)	0.335 (3)	0.2745 (11)	0.045 (11)*
H13	0.689 (6)	1.0076 (12)	−0.060 (2)	0.061 (14)*
H15	0.710 (5)	1.511 (3)	−0.0201 (13)	0.049 (12)*
H16	0.416 (6)	1.629 (4)	−0.2551 (13)	0.054 (12)*
H1w1	1.193 (7)	0.315 (5)	0.412 (3)	0.12 (2)*
H1w2	1.358 (4)	0.293 (6)	0.372 (4)	0.13 (3)*
H2w1	1.280 (5)	0.683 (3)	0.608 (2)	0.055 (13)*
H2w2	1.293 (5)	0.7797 (11)	0.623 (2)	0.046 (11)*
H3w1	0.994 (6)	0.825 (4)	−0.092 (2)	0.073 (16)*
H3w2	0.855 (4)	0.791 (5)	−0.124 (3)	0.12 (3)*
H4w1	0.544 (4)	1.189 (3)	0.112 (3)	0.091 (19)*
H4w2	0.425 (5)	1.2913 (11)	0.114 (2)	0.045 (11)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0350 (11)	0.0155 (11)	0.0266 (10)	−0.0025 (8)	0.0079 (8)	−0.0112 (8)
O2	0.0478 (12)	0.0167 (10)	0.0235 (10)	−0.0033 (9)	0.0084 (9)	−0.0084 (8)
O3	0.0251 (9)	0.0119 (10)	0.0149 (9)	−0.0010 (7)	0.0031 (7)	−0.0049 (7)
O4	0.0350 (11)	0.0174 (10)	0.0181 (10)	−0.0018 (8)	0.0062 (8)	−0.0030 (8)
O5	0.0351 (11)	0.0157 (11)	0.0237 (10)	−0.0015 (8)	0.0047 (8)	−0.0099 (8)
O6	0.0437 (12)	0.0168 (10)	0.0246 (10)	−0.0057 (9)	0.0097 (9)	−0.0087 (8)
O7	0.0269 (10)	0.0138 (9)	0.0170 (9)	−0.0024 (7)	0.0049 (7)	−0.0064 (7)
O8	0.0351 (11)	0.0176 (10)	0.0174 (9)	−0.0043 (8)	0.0057 (8)	−0.0024 (8)
O9	0.0362 (11)	0.0163 (11)	0.0247 (10)	−0.0057 (8)	−0.0017 (8)	−0.0099 (8)
O10	0.0464 (12)	0.0152 (10)	0.0230 (10)	−0.0049 (9)	−0.0029 (9)	−0.0081 (8)
O11	0.0292 (10)	0.0120 (10)	0.0146 (9)	−0.0049 (7)	−0.0020 (7)	−0.0046 (7)
O12	0.0348 (11)	0.0158 (10)	0.0168 (9)	−0.0042 (8)	−0.0055 (8)	−0.0027 (7)
O13	0.0368 (11)	0.0161 (11)	0.0245 (10)	−0.0074 (8)	0.0012 (8)	−0.0102 (8)
O14	0.0463 (12)	0.0154 (10)	0.0229 (10)	−0.0037 (9)	−0.0040 (9)	−0.0075 (8)
O15	0.0281 (10)	0.0131 (9)	0.0147 (9)	−0.0041 (7)	−0.0014 (7)	−0.0046 (7)
O16	0.0376 (11)	0.0175 (10)	0.0162 (9)	−0.0053 (8)	−0.0043 (8)	−0.0023 (7)
O1w	0.0593 (15)	0.0198 (11)	0.0204 (10)	−0.0069 (10)	−0.0070 (10)	−0.0061 (8)
O2w	0.0565 (14)	0.0154 (11)	0.0212 (10)	−0.0006 (10)	−0.0084 (9)	−0.0053 (8)
O3w	0.0538 (15)	0.0214 (11)	0.0203 (10)	−0.0014 (10)	0.0076 (9)	−0.0057 (8)
O4w	0.0621 (15)	0.0156 (11)	0.0192 (10)	−0.0077 (10)	0.0083 (10)	−0.0053 (8)
C1	0.0218 (12)	0.0198 (14)	0.0232 (13)	−0.0056 (10)	0.0034 (10)	−0.0126 (11)
C2	0.0175 (12)	0.0183 (14)	0.0195 (12)	−0.0052 (10)	0.0002 (9)	−0.0090 (10)
C3	0.0181 (12)	0.0179 (14)	0.0154 (12)	−0.0061 (10)	0.0007 (9)	−0.0070 (10)
C4	0.0171 (11)	0.0158 (13)	0.0159 (12)	−0.0038 (9)	0.0011 (9)	−0.0080 (10)
C5	0.0198 (12)	0.0175 (14)	0.0152 (12)	−0.0051 (10)	0.0012 (9)	−0.0048 (10)
C6	0.0215 (12)	0.0232 (14)	0.0154 (12)	−0.0066 (10)	0.0038 (9)	−0.0079 (10)
C7	0.0175 (12)	0.0231 (14)	0.0204 (13)	−0.0051 (10)	0.0033 (9)	−0.0127 (11)
C8	0.0228 (13)	0.0182 (14)	0.0237 (13)	−0.0058 (10)	0.0038 (10)	−0.0111 (11)
C9	0.0178 (12)	0.0188 (14)	0.0206 (13)	−0.0058 (10)	0.0014 (9)	−0.0102 (10)
C10	0.0185 (12)	0.0180 (14)	0.0156 (12)	−0.0052 (10)	0.0014 (9)	−0.0078 (10)
C11	0.0175 (11)	0.0192 (14)	0.0176 (12)	−0.0050 (10)	0.0026 (9)	−0.0111 (10)
C12	0.0202 (12)	0.0163 (14)	0.0190 (12)	−0.0059 (10)	−0.0007 (10)	−0.0056 (10)
C13	0.0193 (12)	0.0254 (15)	0.0173 (12)	−0.0077 (10)	0.0031 (9)	−0.0103 (10)
C14	0.0175 (12)	0.0227 (14)	0.0201 (13)	−0.0064 (10)	0.0029 (9)	−0.0126 (10)
C15	0.0216 (13)	0.0190 (14)	0.0226 (13)	−0.0046 (10)	0.0032 (10)	−0.0104 (11)
C16	0.0173 (12)	0.0172 (13)	0.0211 (13)	−0.0042 (10)	0.0036 (10)	−0.0089 (10)
C17	0.0172 (11)	0.0161 (13)	0.0155 (12)	−0.0034 (10)	0.0032 (9)	−0.0059 (10)
C18	0.0175 (11)	0.0164 (13)	0.0180 (12)	−0.0045 (10)	0.0029 (9)	−0.0089 (10)
C19	0.0183 (12)	0.0166 (13)	0.0177 (12)	−0.0029 (10)	0.0021 (9)	−0.0056 (10)
C20	0.0196 (12)	0.0237 (14)	0.0166 (12)	−0.0039 (10)	0.0005 (9)	−0.0090 (10)
C21	0.0178 (12)	0.0215 (14)	0.0219 (13)	−0.0051 (10)	0.0035 (10)	−0.0131 (11)
C22	0.0224 (13)	0.0206 (14)	0.0231 (13)	−0.0049 (11)	0.0023 (10)	−0.0109 (11)
C23	0.0176 (12)	0.0173 (14)	0.0205 (13)	−0.0041 (10)	0.0032 (9)	−0.0083 (10)
C24	0.0186 (12)	0.0170 (13)	0.0144 (12)	−0.0029 (10)	0.0012 (9)	−0.0055 (10)
C25	0.0177 (11)	0.0163 (13)	0.0173 (12)	−0.0047 (10)	0.0032 (9)	−0.0075 (10)
C26	0.0190 (12)	0.0166 (13)	0.0142 (12)	−0.0040 (10)	0.0029 (9)	−0.0031 (10)
C27	0.0199 (12)	0.0261 (15)	0.0146 (12)	−0.0072 (10)	0.0030 (9)	−0.0086 (10)
C28	0.0185 (12)	0.0229 (14)	0.0208 (13)	−0.0070 (10)	0.0049 (10)	−0.0131 (11)

Geometric parameters (Å, º) top

O1—C1	1.321 (3)	C2—C3	1.402 (3)
O1—H1	0.846 (10)	C3—C4	1.369 (4)
O2—C1	1.242 (3)	C3—H3A	0.9500
O3—C4	1.369 (3)	C4—C5	1.408 (3)
O3—H3	0.839 (10)	C5—C6	1.396 (4)
O4—C5	1.341 (3)	C6—C7	1.379 (4)
O4—H4	0.841 (10)	C6—H6	0.9500
O5—C8	1.320 (3)	C7—H7A	0.9500
O5—H5	0.847 (10)	C8—C9	1.457 (4)
O6—C8	1.248 (3)	C9—C14	1.394 (4)
O7—C11	1.371 (3)	C9—C10	1.405 (3)
O7—H7	0.842 (10)	C10—C11	1.368 (4)
O8—C12	1.351 (3)	C10—H10	0.9500
O8—H8	0.839 (10)	C11—C12	1.409 (4)
O9—C15	1.316 (3)	C12—C13	1.391 (4)
O9—H9	0.843 (10)	C13—C14	1.381 (4)
O10—C15	1.239 (3)	C13—H13A	0.9500
O11—C18	1.365 (3)	C14—H14	0.9500
O11—H11	0.840 (10)	C15—C16	1.466 (4)
O12—C19	1.351 (3)	C16—C21	1.394 (4)
O12—H12	0.841 (10)	C16—C17	1.397 (3)
O13—C22	1.314 (3)	C17—C18	1.380 (4)
O13—H13	0.841 (10)	C17—H17A	0.9500
O14—C22	1.247 (3)	C18—C19	1.410 (3)
O15—C25	1.368 (3)	C19—C20	1.388 (4)
O15—H15	0.844 (10)	C20—C21	1.380 (4)
O16—C26	1.350 (3)	C20—H20	0.9500
O16—H16	0.843 (10)	C21—H21	0.9500
O1w—H1w1	0.843 (10)	C22—C23	1.466 (4)
O1w—H1w2	0.842 (10)	C23—C28	1.394 (4)
O2w—H2w1	0.847 (10)	C23—C24	1.398 (4)
O2w—H2w2	0.849 (10)	C24—C25	1.375 (4)
O3w—H3w1	0.845 (10)	C24—H24A	0.9500
O3w—H3w2	0.842 (10)	C25—C26	1.404 (3)
O4w—H4w1	0.848 (10)	C26—C27	1.391 (4)
O4w—H4w2	0.855 (10)	C27—C28	1.388 (4)
C1—C2	1.454 (4)	C27—H27	0.9500
C2—C7	1.401 (4)	C28—H28	0.9500

C1—O1—H1	110 (2)	O8—C12—C11	116.1 (2)
C4—O3—H3	113 (2)	C13—C12—C11	118.9 (2)
C5—O4—H4	112 (3)	C14—C13—C12	120.7 (2)
C8—O5—H5	107 (3)	C14—C13—H13A	119.6
C11—O7—H7	105 (3)	C12—C13—H13A	119.6
C12—O8—H8	111 (3)	C13—C14—C9	120.2 (2)
C15—O9—H9	102 (3)	C13—C14—H14	119.9
C18—O11—H11	116 (3)	C9—C14—H14	119.9
C19—O12—H12	108 (3)	O10—C15—O9	121.9 (2)
C22—O13—H13	119 (3)	O10—C15—C16	122.2 (2)
C25—O15—H15	112 (3)	O9—C15—C16	115.9 (2)
C26—O16—H16	106 (3)	C21—C16—C17	120.1 (2)
H1w1—O1w—H1w2	109 (2)	C21—C16—C15	121.4 (2)
H2w1—O2w—H2w2	107 (2)	C17—C16—C15	118.5 (2)
H3w1—O3w—H3w2	109 (2)	C18—C17—C16	119.8 (2)
H4w1—O4w—H4w2	106 (2)	C18—C17—H17A	120.1
O2—C1—O1	121.1 (2)	C16—C17—H17A	120.1
O2—C1—C2	122.6 (2)	O11—C18—C17	119.2 (2)
O1—C1—C2	116.3 (2)	O11—C18—C19	120.7 (2)
C7—C2—C3	119.6 (2)	C17—C18—C19	120.1 (2)
C7—C2—C1	121.9 (2)	O12—C19—C20	125.2 (2)
C3—C2—C1	118.5 (2)	O12—C19—C18	115.3 (2)
C4—C3—C2	120.1 (2)	C20—C19—C18	119.4 (2)
C4—C3—H3A	120.0	C21—C20—C19	120.5 (2)
C2—C3—H3A	120.0	C21—C20—H20	119.7
O3—C4—C3	119.7 (2)	C19—C20—H20	119.7
O3—C4—C5	119.6 (2)	C20—C21—C16	120.0 (2)
C3—C4—C5	120.7 (2)	C20—C21—H21	120.0
O4—C5—C6	125.2 (2)	C16—C21—H21	120.0
O4—C5—C4	115.7 (2)	O14—C22—O13	121.7 (2)
C6—C5—C4	119.1 (2)	O14—C22—C23	122.8 (2)
C7—C6—C5	120.5 (2)	O13—C22—C23	115.5 (2)
C7—C6—H6	119.8	C28—C23—C24	119.8 (2)
C5—C6—H6	119.8	C28—C23—C22	121.7 (2)
C6—C7—C2	120.1 (2)	C24—C23—C22	118.5 (2)
C6—C7—H7A	120.0	C25—C24—C23	120.4 (2)
C2—C7—H7A	120.0	C25—C24—H24A	119.8
O6—C8—O5	121.6 (2)	C23—C24—H24A	119.8
O6—C8—C9	123.4 (2)	O15—C25—C24	123.1 (2)
O5—C8—C9	115.0 (2)	O15—C25—C26	116.9 (2)
C14—C9—C10	119.2 (2)	C24—C25—C26	120.0 (2)
C14—C9—C8	121.8 (2)	O16—C26—C27	124.9 (2)
C10—C9—C8	119.0 (2)	O16—C26—C25	115.6 (2)
C11—C10—C9	120.5 (2)	C27—C26—C25	119.5 (2)
C11—C10—H10	119.8	C28—C27—C26	120.4 (2)
C9—C10—H10	119.8	C28—C27—H27	119.8
C10—C11—O7	123.2 (2)	C26—C27—H27	119.8
C10—C11—C12	120.4 (2)	C27—C28—C23	119.9 (2)
O7—C11—C12	116.4 (2)	C27—C28—H28	120.1
O8—C12—C13	124.9 (2)	C23—C28—H28	120.1

O2—C1—C2—C7	−176.4 (2)	O10—C15—C16—C21	178.0 (2)
O1—C1—C2—C7	3.1 (4)	O9—C15—C16—C21	−2.1 (4)
O2—C1—C2—C3	2.5 (4)	O10—C15—C16—C17	−1.5 (4)
O1—C1—C2—C3	−177.9 (2)	O9—C15—C16—C17	178.3 (2)
C7—C2—C3—C4	0.1 (4)	C21—C16—C17—C18	0.6 (4)
C1—C2—C3—C4	−178.9 (2)	C15—C16—C17—C18	−179.9 (2)
C2—C3—C4—O3	−178.2 (2)	C16—C17—C18—O11	178.8 (2)
C2—C3—C4—C5	1.3 (4)	C16—C17—C18—C19	−1.1 (4)
O3—C4—C5—O4	−2.7 (3)	O11—C18—C19—O12	1.1 (3)
C3—C4—C5—O4	177.8 (2)	C17—C18—C19—O12	−179.0 (2)
O3—C4—C5—C6	177.8 (2)	O11—C18—C19—C20	−178.9 (2)
C3—C4—C5—C6	−1.7 (4)	C17—C18—C19—C20	1.0 (4)
O4—C5—C6—C7	−178.6 (2)	O12—C19—C20—C21	179.6 (2)
C4—C5—C6—C7	0.7 (4)	C18—C19—C20—C21	−0.4 (4)
C5—C6—C7—C2	0.6 (4)	C19—C20—C21—C16	−0.1 (4)
C3—C2—C7—C6	−1.0 (4)	C17—C16—C21—C20	0.0 (4)
C1—C2—C7—C6	178.0 (2)	C15—C16—C21—C20	−179.5 (2)
O6—C8—C9—C14	175.7 (3)	O14—C22—C23—C28	−175.5 (3)
O5—C8—C9—C14	−3.6 (4)	O13—C22—C23—C28	4.2 (4)
O6—C8—C9—C10	−3.6 (4)	O14—C22—C23—C24	3.5 (4)
O5—C8—C9—C10	177.0 (2)	O13—C22—C23—C24	−176.8 (2)
C14—C9—C10—C11	−0.1 (4)	C28—C23—C24—C25	−0.3 (4)
C8—C9—C10—C11	179.3 (2)	C22—C23—C24—C25	−179.3 (2)
C9—C10—C11—O7	179.5 (2)	C23—C24—C25—O15	−178.7 (2)
C9—C10—C11—C12	−1.1 (4)	C23—C24—C25—C26	2.1 (4)
C10—C11—C12—O8	−179.1 (2)	O15—C25—C26—O16	−1.4 (3)
O7—C11—C12—O8	0.3 (3)	C24—C25—C26—O16	177.8 (2)
C10—C11—C12—C13	1.3 (4)	O15—C25—C26—C27	178.1 (2)
O7—C11—C12—C13	−179.3 (2)	C24—C25—C26—C27	−2.6 (4)
O8—C12—C13—C14	−179.7 (2)	O16—C26—C27—C28	−179.2 (2)
C11—C12—C13—C14	−0.2 (4)	C25—C26—C27—C28	1.3 (4)
C12—C13—C14—C9	−1.1 (4)	C26—C27—C28—C23	0.6 (4)
C10—C9—C14—C13	1.2 (4)	C24—C23—C28—C27	−1.1 (4)
C8—C9—C14—C13	−178.1 (2)	C22—C23—C28—C27	177.9 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O6	0.85 (1)	1.83 (1)	2.678 (3)	178 (3)
O3—H3···O1Wⁱ	0.84 (1)	1.99 (1)	2.803 (3)	163 (3)
O4—H4···O4Wⁱⁱ	0.84 (1)	1.86 (2)	2.674 (3)	163 (4)
O5—H5···O2	0.85 (1)	1.76 (1)	2.593 (3)	170 (4)
O7—H7···O3ⁱⁱⁱ	0.84 (1)	1.91 (1)	2.746 (3)	172 (4)
O8—H8···O3W^iv	0.84 (1)	1.94 (1)	2.772 (3)	171 (4)
O9—H9···O14	0.84 (1)	1.84 (2)	2.664 (3)	166 (5)
O11—H11···O3W^v	0.84 (1)	2.02 (2)	2.824 (3)	161 (4)
O12—H12···O1W	0.84 (1)	1.92 (1)	2.760 (3)	175 (4)
O13—H13···O10	0.84 (1)	1.76 (1)	2.599 (3)	171 (5)
O15—H15···O11^vi	0.84 (1)	1.91 (1)	2.754 (2)	178 (4)
O16—H16···O2W^vii	0.84 (1)	1.92 (2)	2.699 (3)	153 (4)
O1W—H1W1···O2	0.84 (1)	2.36 (5)	2.920 (3)	124 (4)
O1W—H1W2···O2W^viii	0.84 (1)	2.07 (1)	2.911 (4)	173 (7)
O2W—H2W1···O6	0.85 (1)	2.24 (1)	3.071 (3)	168 (4)
O2W—H2W2···O7^ix	0.85 (1)	2.00 (2)	2.823 (3)	165 (4)
O3W—H3W1···O10	0.85 (1)	2.40 (4)	2.933 (3)	122 (3)
O3W—H3W2···O4W^x	0.84 (1)	2.08 (1)	2.920 (4)	174 (6)
O4W—H4W1···O14	0.85 (1)	2.30 (3)	3.079 (3)	152 (5)
O4W—H4W2···O15^xi	0.86 (1)	1.97 (1)	2.806 (3)	164 (4)

Symmetry codes: (i) −x+3, −y, −z+1; (ii) −x+2, −y+1, −z+1; (iii) x−1, y+1, z; (iv) −x+2, −y+2, −z; (v) −x+2, −y+1, −z; (vi) x, y+1, z; (vii) x−1, y+1, z−1; (viii) −x+3, −y+1, −z+1; (ix) −x+2, −y+2, −z+1; (x) −x+1, −y+2, −z; (xi) −x+1, −y+3, −z.

Experimental details

Crystal data
Chemical formula	C₇H₆O₄·H₂O
M_r	172.13
Crystal system, space group	Triclinic, P1
Temperature (K)	100
a, b, c (Å)	7.1105 (3), 12.7807 (5), 17.5318 (7)
α, β, γ (°)	72.491 (4), 89.901 (3), 74.457 (3)
V (Å³)	1458.45 (10)
Z	8
Radiation type	Cu Kα
µ (mm⁻¹)	1.18
Crystal size (mm)	0.20 × 0.10 × 0.10

Data collection
Diffractometer	Agilent Technologies SuperNova Dual diffractometer with Atlas detector
Absorption correction	Multi-scan (CrysAlis PRO; Agilent, 2010)
T_min, T_max	0.798, 0.891
No. of measured, independent and observed [I > 2σ(I)] reflections	9167, 5301, 4910
R_int	0.020
(sin θ/λ)_max (Å⁻¹)	0.609

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.056, 0.161, 1.15
No. of reflections	5301
No. of parameters	513
No. of restraints	24
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.31, −0.35

Computer programs: CrysAlis PRO (Agilent, 2010), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), X-SEED (Barbour, 2001), publCIF (Westrip, 2010).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O6	0.85 (1)	1.83 (1)	2.678 (3)	178 (3)
O3—H3···O1Wⁱ	0.84 (1)	1.99 (1)	2.803 (3)	163 (3)
O4—H4···O4Wⁱⁱ	0.84 (1)	1.86 (2)	2.674 (3)	163 (4)
O5—H5···O2	0.85 (1)	1.76 (1)	2.593 (3)	170 (4)
O7—H7···O3ⁱⁱⁱ	0.84 (1)	1.91 (1)	2.746 (3)	172 (4)
O8—H8···O3W^iv	0.84 (1)	1.94 (1)	2.772 (3)	171 (4)
O9—H9···O14	0.84 (1)	1.84 (2)	2.664 (3)	166 (5)
O11—H11···O3W^v	0.84 (1)	2.02 (2)	2.824 (3)	161 (4)
O12—H12···O1W	0.84 (1)	1.92 (1)	2.760 (3)	175 (4)
O13—H13···O10	0.84 (1)	1.76 (1)	2.599 (3)	171 (5)
O15—H15···O11^vi	0.84 (1)	1.91 (1)	2.754 (2)	178 (4)
O16—H16···O2W^vii	0.84 (1)	1.92 (2)	2.699 (3)	153 (4)
O1W—H1W1···O2	0.84 (1)	2.36 (5)	2.920 (3)	124 (4)
O1W—H1W2···O2W^viii	0.84 (1)	2.07 (1)	2.911 (4)	173 (7)
O2W—H2W1···O6	0.85 (1)	2.24 (1)	3.071 (3)	168 (4)
O2W—H2W2···O7^ix	0.85 (1)	2.00 (2)	2.823 (3)	165 (4)
O3W—H3W1···O10	0.85 (1)	2.40 (4)	2.933 (3)	122 (3)
O3W—H3W2···O4W^x	0.84 (1)	2.08 (1)	2.920 (4)	174 (6)
O4W—H4W1···O14	0.85 (1)	2.30 (3)	3.079 (3)	152 (5)
O4W—H4W2···O15^xi	0.86 (1)	1.97 (1)	2.806 (3)	164 (4)

Acknowledgements

Dr M. Raza Shah of the University of Karachi is thanked for providing the crystal for the study, and the University of Malaya for supporting this study.

References

Agilent (2010). CrysAlis PRO. Agilent Technologies, Yarnton, Oxfordshire, England. Google Scholar
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