Crystal structure of (E)-4-hy­droxy-3-{1-[(4-hy­droxy­phen­yl)imino]­eth­yl}-6-methyl-2H-pyran-2-one

In the title Schiff base, C₁₄H₁₃NO₄, which adopts the phenol–imine tautomeric form, the dihedral angle between the planes of the benzene and heterocyclic (r.m.s. deviation = 0.037 Å) rings is 53.31 (11)°. An intra­molecular O—H...N hydrogen bond closes an S(6) ring. In the crystal, mol­ecules are linked by O—H...O hydrogen bonds to generate C(11) chains propagating in the [010] direction. A weak C—H...O link is also observed, leading to the formation of R⁵₅(32) rings extending parallel to the (101) plane.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.047
• wR factor = 0.148
• Data-to-parameter ratio = 14.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600          8 Report
PLAT922_ALERT_1_C wR2 in the CIF and FCF Differ by ...............     0.0014 Check
PLAT927_ALERT_1_C Reported and Calculated  wR2 Differ by .........     0.0014 Check
PLAT975_ALERT_2_C Check Calcd Residual Density  0.88A From      N1       0.54 eA-3

Alert level G
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF     Please Do !
PLAT180_ALERT_4_G Check Cell Rounding: # of Values Ending with 0 =          3
PLAT199_ALERT_1_G Reported _cell_measurement_temperature ..... (K)        293 Check
PLAT200_ALERT_1_G Reported   _diffrn_ambient_temperature ..... (K)        293 Check
PLAT912_ALERT_4_G Missing # of FCF Reflections Above STh/L=  0.600         10 Note

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   4 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   4 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Hydroxy Schiff bases have been extensively studied due to their biological, photochromic and thermochromic properties (Garnovskii et al., 1993; Hadjoudis et al., 2004). They are potential materials for optical memory and switch devices (Zhao et al., 2007). Proton transfer in these compounds forms the basis for an explanation of the mechanisms of various biological processes where proton transfer is the rate-determining step (Lussier et al., 1987). In general, O-hydroxy Schiff bases exhibit two possible tautomeric forms, the phenol-imine (or benzenoid) and ketoamine (or quinoid) forms. Depending on the tautomers, two types of intra-molecular hydrogen bonds are possible: O—H···N in benzenoid and N—H···O in quinoid tautomers.

As part of our ongoing studies of Schiff bases (Djedouani et al., 2007, 2008), we now describe the synthesis and the structure of the title compound, which takes the form phenol-imine and complete a six-membered pseudocycle via an intramolecular O—H····O hydrogen bond.

The dehydroacetic acid ring and phenyl ring are almost planer with r.m.s deviation for the mean plane are 0.0260 and 0.0027 respectively. The dihedral angle between the two rings is 53.30 (0.05) °. The two torsional angles τ1 (N1—C5—C14—C4) and τ2 (C5—N1—C1—C6) defining the confirmation of the molecule.

The N1—C5 distance of 1.324 (2) Å agree with similar bond in related compounds (Girija & Begum, 2004; Girija et al. 2004), slightly longer than a typical C=N bond (1.283 (4) Å) (Bai & Jing, 2007); but much shorter than the single carbon-nitrogen bond (Table. 1), N1—C1=1.432 (3) Å because of the resonance. The carbon-carbon bond connecting the phenol and imine groups exhibits intermediate distances between a single and a double bond and agree well with those observed in other azomethines. The C5—N1—C14 and C14—C5—N1 bond angle of 117.70 (2)° and 117.47 () ° respectively in the Schiff base ligand are smaller than typical hexagonal of 120°. This is due to the effect of substitution on O of pyron & OH of the DHA ring.

In the crystal, molecules are aligned head to foot along b axis, in columns along to [0 0 1] axis and the structure is stabilized by an O—H···O hydrogen bond and another weak C—H···O interaction, leading to the formation of R₅⁵(32) rings extending parallel to the (101) plane (Fig. 2, Table.1).

Related literature

For photochromic and thermochromic properties of hydroxy Schiff bases, see: Garnovskii et al. (1993); Hadjoudis et al. (2004). For potential materials for optical memory and switch devices, see: Zhao et al. (2007). For proton-transfer processes, see: Lussier et al. (1987). For Schiff base structures, see: Djedouani et al. (2007, 2008) For Schiff base bond lengths and angles, see: Girija & Begum (2004); Girija et al. (2004); Bai & Jing (2007).

S2. Experimental

Compound (I) was prepared by refluxing a mixture of a solution containing dehydroacetic acid (0.01 mmol) and para-4-aminophenol (0.01 mmol) in ethanol (40 ml). The reaction mixture was stirred for 2 h under reflux and left to cool. Yellow crystals grew after a few days.

S3. Refinement

C—H and O—H hydrogen atoms were placed in calculated positions and refined as riding atoms with C—H distances of 0.93 Å with U_iso(H) = 1.2Ueq(C) and O—H distances of 0.82 Å, with U_iso(H) = 1.2Ueq(N).

The methyl H atoms were constrained to an ideal geometry (C—H = 0.96 Å) with U_iso(H) = 1.2Ueq(C), but were allowed to rotate freely about the C—C bonds.

Computing details

Data collection: COLLECT (Nonius, 2002); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: olex2.refine (Dolomanov et al., 2009); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 2012) and PARST (Nardelli, 1995).

Figures

	Fig. 1. The structure of the title compound in 50% probability ellipsoids.
	Fig. 2. Part of the crystal structure of (I), showing the formation of S(6) rings with dashed red lines. C—H···O and O—H···O hydrogen bonds are shown as blue dashed lines.

(E)-4-hydroxy-3-{1-[(4-hydroxyphenyl)imino]ethyl}-6-methyl-2H-pyran-2-one

Crystal data

C14H13NO4	F(000) = 544.3271
Mr = 259.26	Dx = 1.391 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 0 reflections
a = 7.8730 (5) Å	θ = 2.9–27.5°
b = 11.7930 (8) Å	µ = 0.10 mm^−1
c = 13.5330 (8) Å	T = 293 K
β = 99.896 (2)°	Block, yellow
V = 1237.79 (14) Å^3	0.10 × 0.06 × 0.03 mm
Z = 4

Data collection

Nonius KappaCCD diffractometer	2582 independent reflections
Radiation source: Enraf–Nonius FR590	2061 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.026
Detector resolution: 9 pixels mm^-1	θmax = 26.7°, θmin = 2.3°
CCD rotation images, thin slices scans	h = −9→9
Absorption correction: multi-scan (SADABS; Sheldrick, 2002)	k = −14→14
Tmin = 0.875, Tmax = 0.947	l = −17→17
17976 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.148	All H-atom parameters refined
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0655P)^2 + 0.6848P] where P = (Fo^2 + 2Fc^2)/3
2582 reflections	(Δ/σ)max = 0.005
173 parameters	Δρmax = 0.54 e Å^−3
0 restraints	Δρmin = −0.38 e Å^−3

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

	x	y	z	Uiso*/Ueq
O1	0.6637 (2)	−0.08723 (12)	0.50633 (10)	0.0520 (4)
H1	0.6696 (2)	−0.05535 (12)	0.45317 (10)	0.0779 (6)*
O2	0.4993 (2)	0.21003 (13)	−0.00201 (10)	0.0543 (4)
H2	0.4624 (2)	0.27519 (13)	−0.00450 (10)	0.0815 (7)*
O3	1.0343 (3)	0.20593 (17)	0.65333 (13)	0.0814 (7)
O4	0.92760 (19)	0.08216 (12)	0.74439 (9)	0.0443 (4)
C1	0.6821 (3)	0.11371 (17)	0.29043 (13)	0.0390 (4)
C2	0.7568 (3)	−0.07161 (18)	0.67874 (15)	0.0444 (5)
H2a	0.7031 (3)	−0.13959 (18)	0.68968 (15)	0.0533 (6)*
C3	0.6279 (3)	0.07382 (18)	0.11415 (14)	0.0433 (5)
H3	0.6333 (3)	0.02421 (18)	0.06136 (14)	0.0520 (6)*
C4	0.7488 (3)	−0.03156 (16)	0.57810 (14)	0.0391 (4)
C5	0.8305 (3)	0.12191 (16)	0.46720 (14)	0.0382 (4)
C6	0.6138 (3)	0.22135 (17)	0.27136 (14)	0.0416 (5)
H6	0.6089 (3)	0.27092 (17)	0.32425 (14)	0.0499 (6)*
C7	0.5531 (3)	0.25514 (17)	0.17428 (14)	0.0416 (5)
H7	0.5074 (3)	0.32751 (17)	0.16191 (14)	0.0499 (6)*
C8	0.8390 (3)	−0.01396 (17)	0.75665 (14)	0.0407 (5)
C9	0.9259 (3)	0.22691 (19)	0.44950 (16)	0.0489 (5)
H9a	0.9215 (18)	0.2372 (8)	0.37874 (17)	0.0733 (8)*
H9b	0.8738 (13)	0.2909 (3)	0.4764 (11)	0.0733 (8)*
H9c	1.0438 (6)	0.2203 (6)	0.4820 (10)	0.0733 (8)*
C10	0.5598 (3)	0.18172 (17)	0.09476 (13)	0.0389 (4)
C11	0.9398 (3)	0.12553 (18)	0.65006 (15)	0.0454 (5)
C12	0.8492 (3)	−0.0416 (2)	0.86465 (15)	0.0554 (6)
H12a	0.9678 (4)	−0.0434 (15)	0.8967 (3)	0.0831 (9)*
H12b	0.789 (2)	0.0151 (9)	0.8959 (3)	0.0831 (9)*
H12c	0.797 (2)	−0.1144 (7)	0.87109 (15)	0.0831 (9)*
C13	0.6877 (3)	0.03998 (17)	0.21150 (15)	0.0419 (5)
H13	0.7319 (3)	−0.03271 (17)	0.22414 (15)	0.0502 (6)*
C14	0.8397 (2)	0.07122 (16)	0.56378 (13)	0.0368 (4)
N1	0.7321 (2)	0.07168 (14)	0.39048 (12)	0.0434 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0748 (11)	0.0408 (8)	0.0347 (7)	−0.0120 (7)	−0.0066 (7)	0.0022 (6)
O2	0.0822 (11)	0.0507 (9)	0.0265 (7)	0.0122 (8)	−0.0009 (7)	0.0018 (6)
O3	0.1131 (16)	0.0775 (13)	0.0444 (9)	−0.0536 (12)	−0.0125 (9)	0.0064 (9)
O4	0.0563 (9)	0.0434 (8)	0.0295 (7)	−0.0021 (6)	−0.0029 (6)	−0.0003 (6)
C1	0.0454 (11)	0.0404 (10)	0.0286 (9)	−0.0016 (8)	−0.0009 (7)	0.0027 (8)
C2	0.0565 (13)	0.0373 (10)	0.0383 (10)	−0.0024 (9)	0.0051 (9)	0.0042 (8)
C3	0.0508 (12)	0.0445 (11)	0.0329 (10)	0.0055 (9)	0.0021 (8)	−0.0065 (8)
C4	0.0466 (11)	0.0347 (10)	0.0332 (9)	0.0032 (8)	−0.0009 (8)	−0.0006 (8)
C5	0.0431 (10)	0.0367 (10)	0.0329 (9)	0.0046 (8)	0.0012 (8)	0.0004 (8)
C6	0.0557 (12)	0.0394 (10)	0.0290 (9)	0.0000 (9)	0.0052 (8)	−0.0029 (8)
C7	0.0532 (12)	0.0359 (10)	0.0343 (10)	0.0040 (9)	0.0036 (8)	0.0028 (8)
C8	0.0475 (11)	0.0389 (10)	0.0346 (10)	0.0077 (8)	0.0046 (8)	0.0027 (8)
C9	0.0536 (13)	0.0506 (12)	0.0397 (11)	−0.0060 (10)	0.0007 (9)	0.0079 (9)
C10	0.0451 (11)	0.0425 (11)	0.0275 (9)	0.0004 (8)	0.0018 (7)	0.0032 (8)
C11	0.0555 (13)	0.0423 (11)	0.0348 (10)	−0.0052 (10)	−0.0028 (9)	0.0032 (8)
C12	0.0773 (16)	0.0557 (14)	0.0329 (11)	0.0044 (12)	0.0088 (10)	0.0034 (9)
C13	0.0462 (11)	0.0379 (10)	0.0385 (10)	0.0066 (8)	−0.0008 (8)	0.0005 (8)
C14	0.0439 (11)	0.0336 (9)	0.0306 (9)	0.0029 (8)	−0.0002 (8)	0.0021 (7)
N1	0.0560 (10)	0.0414 (9)	0.0290 (8)	−0.0014 (8)	−0.0033 (7)	0.0036 (7)

Geometric parameters (Å, º)

O1—H1	0.82	C5—C9	1.489 (3)
O1—C4	1.265 (2)	C5—C14	1.428 (3)
O2—H2	0.82	C5—N1	1.324 (2)
O2—C10	1.356 (2)	C6—H6	0.93
O3—C11	1.201 (3)	C6—C7	1.377 (3)
O4—C8	1.356 (2)	C7—H7	0.93
O4—C11	1.394 (2)	C7—C10	1.389 (3)
C1—C6	1.385 (3)	C8—C12	1.486 (3)
C1—C13	1.384 (3)	C9—H9a	0.96
C1—N1	1.432 (2)	C9—H9b	0.96
C2—H2a	0.93	C9—H9c	0.96
C2—C4	1.433 (3)	C11—C14	1.442 (3)
C2—C8	1.326 (3)	C12—H12a	0.96
C3—H3	0.93	C12—H12b	0.96
C3—C10	1.388 (3)	C12—H12c	0.96
C3—C13	1.380 (3)	C13—H13	0.93
C4—C14	1.438 (3)
C4—O1—H1	109.5	C12—C8—C2	127.3 (2)
C10—O2—H2	109.5	H9a—C9—C5	109.5
C11—O4—C8	122.46 (15)	H9b—C9—C5	109.5
C13—C1—C6	119.66 (17)	H9b—C9—H9a	109.5
N1—C1—C6	121.88 (17)	H9c—C9—C5	109.5
N1—C1—C13	118.18 (18)	H9c—C9—H9a	109.5
C4—C2—H2a	119.25 (12)	H9c—C9—H9b	109.5
C8—C2—H2a	119.25 (12)	C3—C10—O2	117.93 (17)
C8—C2—C4	121.5 (2)	C7—C10—O2	122.75 (18)
C10—C3—H3	119.90 (11)	C7—C10—C3	119.31 (17)
C13—C3—H3	119.90 (12)	O4—C11—O3	113.30 (18)
C13—C3—C10	120.19 (18)	C14—C11—O3	129.00 (19)
C2—C4—O1	119.33 (18)	C14—C11—O4	117.69 (18)
C14—C4—O1	122.99 (17)	H12a—C12—C8	109.5
C14—C4—C2	117.68 (17)	H12b—C12—C8	109.5
C14—C5—C9	123.23 (17)	H12b—C12—H12a	109.5
N1—C5—C9	119.29 (17)	H12c—C12—C8	109.5
N1—C5—C14	117.48 (18)	H12c—C12—H12a	109.5
H6—C6—C1	119.91 (11)	H12c—C12—H12b	109.5
C7—C6—C1	120.17 (18)	C3—C13—C1	120.30 (18)
C7—C6—H6	119.91 (12)	H13—C13—C1	119.85 (11)
H7—C7—C6	119.82 (12)	H13—C13—C3	119.85 (12)
C10—C7—C6	120.36 (18)	C5—C14—C4	121.89 (17)
C10—C7—H7	119.82 (11)	C11—C14—C4	118.74 (17)
C2—C8—O4	121.50 (18)	C11—C14—C5	119.35 (18)
C12—C8—O4	111.21 (18)	C5—N1—C1	127.99 (17)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1	0.82	1.83	2.560 (2)	147
O2—H2···O1^i	0.82	1.90	2.710 (2)	169
C12—H12B···O3^ii	0.96	2.55	3.137 (3)	120

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