2,2-Bis(hydroxy­meth­yl)propane-1,3-diyl bis­(1H-pyrrole-2-carboxyl­ate)

The title compound, C₁₅H₁₈N₂O₆, has two pyrrole–carboxyl­ate groups which show different conformations. It forms tapes via N—H...O and O—H...O hydrogen bonds. The tapes are connected through pairs of N—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.041
• wR factor = 0.099
• Data-to-parameter ratio = 12.2

checkCIF/PLATON results

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Alert level C
PLAT230_ALERT_2_C Hirshfeld Test Diff for    C14    -   C15     ..       5.43 su

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 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
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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S1. Comment

Pyrrole-based compounds have frequently been observed as hosts for neutral molecules (Fang et al., 2004) and anionic species (Yin et al., 2004). It was found that these compounds also have the ability to form higher-order self-assembled ensembles and aggregates in the solid state via hydrogen bonds (Sessler et al., 2003). Here, we report the self-assembly of the title compound, (I), via conventional N—H···O and O—H···O hydrogen bonds.

Treatment of 2-trichloroacetylpyrrole with pentaerythritol and triethylamine in refluxed acetonitrile solution gave the title compound directly. The molecular structure of (I) is shown in Fig. 1.

Compound (I) possesses two pyrrole-2-carboxylate moieties and two hydroxyl groups. Interestingly, in the solid state, the two pyrrole-2-carboxylate moieties have different conformations. One is in a syn conformation, with the carbonyl group arranged syn to its adjacent pyrrole NH group, and the other is in an anti conformation, with the carbonyl group arranged anti to its adjacent pyrrole NH group.

There is an intramolecular O—H···O hydrogen bond between the hydroxyl group (O3—H) and the carbonyl group (O6═C11) from the syn pyrrole-2-carboxylate moiety [O···O 2.937 (2) Å and 150 (3)°]. Molecules of (I) assemble as a tape through N—H···O [N···O 2.989 (3) Å and 173 (2)°] and O—H···O hydrogen bonds [O···O 2.769 (2) Å and 166 (2)°], as shown in Fig. 2. The tapes are further linked by a pair of N—H···O hydrogen bonds [N···O 2.936 (3) Å and 160 (2)°] between neighbouring syn pyrrole-2-carboxylate moieties (Fig. 3).

S2. Experimental

2-Trichloroacetylpyrrole (527 mg, 2.5 mmol), pentaerythritol (136 mg, 1 mmol) and triethylamine (0.5 ml) were added to an acetonitrile solution Of what? (20 ml), and the mixture was refluxed for 12 h. The solution was evaporated under reduced pressure and the residue was purified by column chromatography on silica gel with ethyl acetate–petroleum ether (2:1 v/v), affording the title compound (177 mg, 55%). Spectroscopic analysis: ¹H NMR (300 MHz, CDCl₃, δ, p.p.m.): 9.20 (b, 2H, NH), 6.99 (s, 2H, –CH–), 6.96 (s, 2H, –CH–), 6.29 (s, 2H, –CH–), 4.40 (s, 4H, –CH₂—O), 3.66 (d, 4H, J = 4.8 Hz, –CH₂—OH). ESI-MS (m/z): 322.9 (M+H⁺). Analysis calculated for C₁₅H₁₈N₂O₆: C 55.90, H 5.63, N 8.69%; found: C 55.67, H 5.64, N 8.66%.

S3. Refinement

H atoms bound to O and N were located in a difference map and refined freely. Other H atoms were placed in difference Fourier map [Positioned geometrically?], with C—H = 0.93 or 0.97 Å, and included in the final cycles of refinement using a riding model, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure and atomic numbering scheme of (I), drawn with 30% probability ellipsoids.
	Fig. 2. The tape-like self-assembly of molecules of (I) via O—H···O and N—H···O hydrogen bonds (dashed lines). [Symmetry codes: (A) x − 1, y, z; (B) x, y, z; (C) x + 1, y, z.]
	Fig. 3. A crystal packing diagram, showing tapes held together via pairs of N—H···O hydrogen bonds (dashed lines).

2,2-Bis(hydroxymethyl)propane-1,3-diyl bis(1H-pyrrole-2-carboxylate)

Crystal data

C15H18N2O6	Z = 2
Mr = 322.31	F(000) = 340
Triclinic, P1	Dx = 1.380 Mg m^−3
Hall symbol: -P 1	Melting point: 411 K
a = 6.434 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.212 (3) Å	Cell parameters from 1172 reflections
c = 13.715 (4) Å	θ = 2.3–24.7°
α = 73.202 (5)°	µ = 0.11 mm^−1
β = 85.533 (5)°	T = 294 K
γ = 89.330 (5)°	Block, colourless
V = 775.8 (4) Å^3	0.32 × 0.20 × 0.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer	2713 independent reflections
Radiation source: fine-focus sealed tube	1733 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.021
ϕ and ω scans	θmax = 25.0°, θmin = 1.6°
Absorption correction: multi-scan (SADABS; Bruker, 1997)	h = −7→6
Tmin = 0.949, Tmax = 0.989	k = −10→10
3971 measured reflections	l = −16→16

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.099	H atoms treated by a mixture of independent and constrained refinement
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0421P)^2 + 0.0475P] where P = (Fo^2 + 2Fc^2)/3
2713 reflections	(Δ/σ)max = 0.001
222 parameters	Δρmax = 0.15 e Å^−3
0 restraints	Δρmin = −0.16 e Å^−3

Special details

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 > 2σ(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 (Ų)

	x	y	z	Uiso*/Ueq
O1	0.1565 (2)	0.2613 (2)	1.17072 (12)	0.0699 (5)
O2	0.4200 (2)	0.28789 (16)	1.04926 (10)	0.0398 (4)
O3	0.6099 (2)	0.3316 (2)	0.82510 (12)	0.0623 (5)
H3	0.598 (4)	0.377 (3)	0.765 (2)	0.093*
O4	−0.1119 (2)	0.2491 (2)	0.97534 (12)	0.0576 (5)
H4	−0.185 (4)	0.288 (3)	0.923 (2)	0.086*
O5	0.0965 (2)	0.38472 (16)	0.72687 (10)	0.0398 (4)
O6	0.4046 (2)	0.45053 (19)	0.63450 (11)	0.0550 (4)
N1	0.6851 (3)	0.1343 (2)	1.18723 (15)	0.0436 (5)
H1	0.738 (3)	0.174 (2)	1.1290 (16)	0.047 (7)*
N2	0.2372 (4)	0.3609 (2)	0.47449 (14)	0.0497 (5)
H2	0.355 (4)	0.407 (3)	0.457 (2)	0.075 (10)*
C1	0.7764 (4)	0.0464 (3)	1.26842 (19)	0.0543 (6)
H1A	0.9171	0.0222	1.2700	0.065*
C2	0.6284 (4)	−0.0015 (3)	1.34805 (17)	0.0555 (7)
H2A	0.6494	−0.0643	1.4129	0.067*
C3	0.4411 (4)	0.0611 (3)	1.31409 (16)	0.0499 (6)
H3A	0.3134	0.0484	1.3525	0.060*
C4	0.4770 (3)	0.1454 (2)	1.21380 (15)	0.0366 (5)
C5	0.3338 (3)	0.2349 (2)	1.14564 (15)	0.0395 (5)
C6	0.2990 (3)	0.3878 (2)	0.97391 (15)	0.0394 (5)
H6A	0.3781	0.4802	0.9409	0.047*
H6B	0.1722	0.4148	1.0074	0.047*
C7	0.2428 (3)	0.3129 (2)	0.89353 (14)	0.0291 (5)
C8	0.4321 (3)	0.2343 (2)	0.85818 (15)	0.0409 (5)
H8A	0.4671	0.1478	0.9140	0.049*
H8B	0.3961	0.1966	0.8025	0.049*
C9	0.0738 (3)	0.1922 (2)	0.93779 (15)	0.0407 (5)
H9A	0.0406	0.1467	0.8853	0.049*
H9B	0.1278	0.1132	0.9930	0.049*
C10	0.1661 (3)	0.4408 (2)	0.80711 (14)	0.0376 (5)
H10A	0.0519	0.4917	0.8336	0.045*
H10B	0.2779	0.5143	0.7792	0.045*
C11	0.2267 (3)	0.3999 (2)	0.64317 (15)	0.0393 (5)
C12	0.1320 (3)	0.3482 (2)	0.56765 (15)	0.0393 (5)
C13	−0.0548 (4)	0.2787 (2)	0.56928 (17)	0.0493 (6)
H13	−0.1572	0.2549	0.6233	0.059*
C14	−0.0646 (4)	0.2495 (3)	0.4755 (2)	0.0627 (7)
H14	−0.1740	0.2025	0.4555	0.075*
C15	0.1164 (5)	0.3030 (3)	0.41866 (19)	0.0620 (7)
H15	0.1509	0.3000	0.3522	0.074*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0461 (10)	0.1040 (15)	0.0467 (10)	0.0214 (10)	0.0048 (8)	−0.0042 (10)
O2	0.0359 (8)	0.0525 (9)	0.0283 (8)	0.0014 (7)	−0.0069 (6)	−0.0064 (7)
O3	0.0288 (9)	0.1025 (15)	0.0434 (10)	−0.0074 (9)	−0.0005 (8)	−0.0023 (10)
O4	0.0265 (8)	0.0978 (14)	0.0411 (10)	−0.0010 (8)	0.0002 (7)	−0.0091 (9)
O5	0.0347 (8)	0.0574 (10)	0.0255 (7)	−0.0007 (7)	−0.0022 (6)	−0.0091 (7)
O6	0.0402 (9)	0.0808 (12)	0.0365 (9)	−0.0071 (9)	0.0014 (7)	−0.0060 (8)
N1	0.0430 (12)	0.0484 (12)	0.0347 (11)	−0.0006 (9)	−0.0044 (10)	−0.0043 (10)
N2	0.0628 (15)	0.0514 (13)	0.0322 (11)	0.0127 (11)	−0.0017 (11)	−0.0087 (10)
C1	0.0528 (15)	0.0543 (15)	0.0553 (15)	0.0115 (12)	−0.0205 (13)	−0.0114 (12)
C2	0.0762 (18)	0.0518 (15)	0.0353 (13)	0.0120 (13)	−0.0126 (13)	−0.0055 (11)
C3	0.0584 (15)	0.0551 (15)	0.0319 (12)	0.0056 (12)	0.0011 (11)	−0.0072 (11)
C4	0.0384 (12)	0.0402 (12)	0.0308 (11)	0.0007 (10)	−0.0020 (10)	−0.0097 (10)
C5	0.0418 (13)	0.0459 (14)	0.0302 (12)	−0.0002 (11)	−0.0006 (10)	−0.0108 (10)
C6	0.0473 (13)	0.0354 (12)	0.0342 (12)	−0.0019 (10)	−0.0115 (10)	−0.0059 (10)
C7	0.0252 (10)	0.0341 (12)	0.0272 (10)	−0.0024 (9)	−0.0013 (8)	−0.0074 (9)
C8	0.0346 (12)	0.0519 (14)	0.0337 (12)	0.0041 (11)	−0.0034 (10)	−0.0085 (10)
C9	0.0369 (12)	0.0462 (14)	0.0374 (12)	−0.0084 (10)	−0.0041 (10)	−0.0091 (10)
C10	0.0409 (12)	0.0418 (13)	0.0289 (11)	0.0027 (10)	−0.0045 (9)	−0.0082 (10)
C11	0.0398 (13)	0.0446 (13)	0.0278 (11)	0.0070 (11)	−0.0012 (10)	−0.0019 (10)
C12	0.0474 (13)	0.0402 (13)	0.0266 (11)	0.0095 (11)	−0.0035 (10)	−0.0040 (9)
C13	0.0588 (15)	0.0451 (14)	0.0427 (14)	0.0015 (12)	−0.0094 (12)	−0.0093 (11)
C14	0.083 (2)	0.0540 (17)	0.0570 (17)	0.0002 (14)	−0.0217 (15)	−0.0211 (14)
C15	0.103 (2)	0.0519 (16)	0.0357 (13)	0.0220 (15)	−0.0165 (15)	−0.0180 (12)

Geometric parameters (Å, º)

O1—C5	1.208 (2)	C3—H3A	0.9300
O2—C5	1.346 (2)	C4—C5	1.440 (3)
O2—C6	1.442 (2)	C6—C7	1.526 (3)
O3—C8	1.423 (2)	C6—H6A	0.9700
O3—H3	0.82 (3)	C6—H6B	0.9700
O4—C9	1.418 (2)	C7—C10	1.519 (3)
O4—H4	0.87 (3)	C7—C9	1.524 (3)
O5—C11	1.341 (2)	C7—C8	1.528 (3)
O5—C10	1.445 (2)	C8—H8A	0.9700
O6—C11	1.225 (2)	C8—H8B	0.9700
N1—C1	1.346 (3)	C9—H9A	0.9700
N1—C4	1.371 (3)	C9—H9B	0.9700
N1—H1	0.82 (2)	C10—H10A	0.9700
N2—C15	1.347 (3)	C10—H10B	0.9700
N2—C12	1.373 (3)	C11—C12	1.436 (3)
N2—H2	0.86 (2)	C12—C13	1.364 (3)
C1—C2	1.365 (3)	C13—C14	1.394 (3)
C1—H1A	0.9300	C13—H13	0.9300
C2—C3	1.384 (3)	C14—C15	1.363 (3)
C2—H2A	0.9300	C14—H14	0.9300
C3—C4	1.373 (3)	C15—H15	0.9300
C5—O2—C6	118.39 (16)	C9—C7—C8	107.32 (16)
C8—O3—H3	107 (2)	C6—C7—C8	110.68 (15)
C9—O4—H4	107.1 (17)	O3—C8—C7	113.00 (18)
C11—O5—C10	117.84 (16)	O3—C8—H8A	109.0
C1—N1—C4	109.05 (19)	C7—C8—H8A	109.0
C1—N1—H1	128.4 (15)	O3—C8—H8B	109.0
C4—N1—H1	122.5 (15)	C7—C8—H8B	109.0
C15—N2—C12	108.7 (2)	H8A—C8—H8B	107.8
C15—N2—H2	128.8 (18)	O4—C9—C7	113.58 (17)
C12—N2—H2	122.2 (18)	O4—C9—H9A	108.8
N1—C1—C2	108.7 (2)	C7—C9—H9A	108.8
N1—C1—H1A	125.6	O4—C9—H9B	108.8
C2—C1—H1A	125.6	C7—C9—H9B	108.8
C1—C2—C3	107.2 (2)	H9A—C9—H9B	107.7
C1—C2—H2A	126.4	O5—C10—C7	111.36 (16)
C3—C2—H2A	126.4	O5—C10—H10A	109.4
C4—C3—C2	108.0 (2)	C7—C10—H10A	109.4
C4—C3—H3A	126.0	O5—C10—H10B	109.4
C2—C3—H3A	126.0	C7—C10—H10B	109.4
N1—C4—C3	107.05 (19)	H10A—C10—H10B	108.0
N1—C4—C5	123.65 (18)	O6—C11—O5	123.1 (2)
C3—C4—C5	129.3 (2)	O6—C11—C12	125.29 (19)
O1—C5—O2	122.98 (19)	O5—C11—C12	111.61 (19)
O1—C5—C4	124.73 (19)	C13—C12—N2	107.6 (2)
O2—C5—C4	112.29 (18)	C13—C12—C11	132.0 (2)
O2—C6—C7	111.25 (16)	N2—C12—C11	120.4 (2)
O2—C6—H6A	109.4	C12—C13—C14	107.8 (2)
C7—C6—H6A	109.4	C12—C13—H13	126.1
O2—C6—H6B	109.4	C14—C13—H13	126.1
C7—C6—H6B	109.4	C15—C14—C13	107.1 (2)
H6A—C6—H6B	108.0	C15—C14—H14	126.5
C10—C7—C9	111.19 (15)	C13—C14—H14	126.5
C10—C7—C6	105.22 (15)	N2—C15—C14	108.9 (2)
C9—C7—C6	110.47 (16)	N2—C15—H15	125.6
C10—C7—C8	112.00 (16)	C14—C15—H15	125.6
C4—N1—C1—C2	0.5 (3)	C10—C7—C9—O4	−58.0 (2)
N1—C1—C2—C3	−0.6 (3)	C6—C7—C9—O4	58.4 (2)
C1—C2—C3—C4	0.5 (3)	C8—C7—C9—O4	179.14 (15)
C1—N1—C4—C3	−0.2 (2)	C11—O5—C10—C7	−100.45 (19)
C1—N1—C4—C5	178.1 (2)	C9—C7—C10—O5	−57.4 (2)
C2—C3—C4—N1	−0.2 (3)	C6—C7—C10—O5	−177.02 (15)
C2—C3—C4—C5	−178.4 (2)	C8—C7—C10—O5	62.7 (2)
C6—O2—C5—O1	3.7 (3)	C10—O5—C11—O6	4.4 (3)
C6—O2—C5—C4	−176.00 (16)	C10—O5—C11—C12	−176.30 (16)
N1—C4—C5—O1	−170.5 (2)	C15—N2—C12—C13	1.1 (2)
C3—C4—C5—O1	7.4 (4)	C15—N2—C12—C11	179.25 (19)
N1—C4—C5—O2	9.2 (3)	O6—C11—C12—C13	173.9 (2)
C3—C4—C5—O2	−172.9 (2)	O5—C11—C12—C13	−5.4 (3)
C5—O2—C6—C7	−112.97 (19)	O6—C11—C12—N2	−3.7 (3)
O2—C6—C7—C10	−166.22 (15)	O5—C11—C12—N2	176.99 (17)
O2—C6—C7—C9	73.7 (2)	N2—C12—C13—C14	−0.5 (2)
O2—C6—C7—C8	−45.0 (2)	C11—C12—C13—C14	−178.3 (2)
C10—C7—C8—O3	64.1 (2)	C12—C13—C14—C15	−0.4 (3)
C9—C7—C8—O3	−173.64 (16)	C12—N2—C15—C14	−1.4 (3)
C6—C7—C8—O3	−53.0 (2)	C13—C14—C15—N2	1.1 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O6	0.82 (3)	2.20 (3)	2.937 (2)	150 (3)
O4—H4···O3^i	0.87 (3)	1.92 (3)	2.769 (2)	166 (2)
N1—H1···O4^ii	0.82 (2)	2.17 (2)	2.989 (3)	173 (2)
N2—H2···O6^iii	0.86 (2)	2.12 (3)	2.936 (3)	160 (2)

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