Synthesis, structural characterization and luminescence properties of 1-carb­oxy­methyl-3-ethyl­imidazolium chloride

A microcrystalline carboxyl-functionalized imidazolium chloride, namely 1-carb­oxy­methyl-3-ethyl­imidazolium chloride, C₇H₁₁N₂O₂⁺·Cl⁻, has been synthesized and characterized by elemental analysis, attenuated total reflectance Fourier transform IR spectroscopy (ATR-FT-IR), single-crystal X-ray diffraction, thermal analysis (TGA/DSC), and photoluminescence spectroscopy. In the crystal structure, cations and anions are linked by C—H...Cl and C—H...O hydrogen bonds to create a helix along the [010] direction. Adjacent helical chains are further inter­connected through O—H...Cl and C—H...O hydrogen bonds to form a (10) layer. Finally, neighboring layers are joined together via C—H...Cl contacts to generate a three-dimensional supra­molecular architecture. Thermal analyses reveal that the compound melts at 449.7 K and is stable up to 560.0 K under a dynamic air atmosphere. Photoluminescence measurements show that the compound exhibits a blue fluorescence and a green phospho­rescence associated with spin-allowed (¹π←¹π*) and spin-forbidden (¹π←³π*) transitions, respectively. The average luminescence lifetime was determined to be 1.40 ns for the short-lived (¹π←¹π*) transition and 105 ms for the long-lived (¹π←³π*) transition.

Computing details

Data collection: SMART (Bruker, 2002); cell refinement: SAINT (Bruker, 2002); data reduction: SAINT (Bruker, 2002); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 1999); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015b).

1-Carboxymethyl-3-ethylimidazolium chloride

Crystal data

C7H11N2O2^+·Cl^−	Dx = 1.347 Mg m^−3
Mr = 190.63	Melting point: 446.1 K
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 10.2225 (16) Å	Cell parameters from 4273 reflections
b = 9.6736 (16) Å	θ = 3.0–26.2°
c = 10.2678 (17) Å	µ = 0.37 mm^−1
β = 112.165 (8)°	T = 294 K
V = 940.3 (3) Å^3	Parallelepiped, colourless
Z = 4	0.10 × 0.10 × 0.10 mm
F(000) = 400

Data collection

Bruker APEX CCD diffractometer	1844 independent reflections
Radiation source: fine-focus sealed tube	1557 reflections with I > 2σ(I)
Detector resolution: 8.33 pixels mm^-1	Rint = 0.031
ω scans	θmax = 26.0°, θmin = 3.0°
Absorption correction: empirical (using intensity measurements) (Blessing, 1995)	h = −12→12
Tmin = 0.911, Tmax = 0.983	k = −11→11
12035 measured reflections	l = −12→12

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F^2 > 2σ(F^2)] = 0.036	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.106	w = 1/[σ^2(Fo^2) + (0.0564P)^2 + 0.1633P] where P = (Fo^2 + 2Fc^2)/3
S = 1.10	(Δ/σ)max < 0.001
1844 reflections	Δρmax = 0.23 e Å^−3
112 parameters	Δρmin = −0.20 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.

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

	x	y	z	Uiso*/Ueq
C1	0.13632 (17)	0.67336 (15)	−0.00212 (17)	0.0422 (4)
H1	0.0773	0.7390	0.0133	0.051*
C2	0.2695 (2)	0.56244 (18)	−0.09152 (19)	0.0528 (4)
H2A	0.3172	0.5395	−0.1498	0.063*
C3	0.2714 (2)	0.49169 (18)	0.0212 (2)	0.0552 (5)
H3	0.3207	0.4104	0.0560	0.066*
C4	0.16677 (18)	0.52539 (17)	0.20420 (16)	0.0448 (4)
H4B	0.1726	0.4258	0.2162	0.054*
H4A	0.0733	0.5543	0.1966	0.054*
C5	0.27599 (17)	0.59300 (16)	0.33095 (16)	0.0425 (4)
C6	0.1495 (2)	0.7779 (2)	−0.2195 (2)	0.0571 (5)
H6A	0.2362	0.8134	−0.2245	0.069*
H6B	0.0990	0.8548	−0.1996	0.069*
C7	0.0606 (2)	0.7146 (3)	−0.3581 (2)	0.0749 (6)
H7A	0.0397	0.7831	−0.4308	0.112*
H7B	0.1111	0.6394	−0.3785	0.112*
H7C	−0.0259	0.6808	−0.3537	0.112*
N1	0.18375 (14)	0.67547 (12)	−0.10510 (14)	0.0414 (3)
N2	0.18709 (14)	0.56148 (13)	0.07581 (13)	0.0405 (3)
O1	0.35277 (13)	0.68432 (12)	0.32434 (13)	0.0516 (3)
O2	0.27241 (16)	0.54072 (15)	0.44750 (13)	0.0652 (4)
H2	0.338 (3)	0.587 (3)	0.528 (3)	0.098*
Cl1	0.53307 (5)	0.32422 (5)	0.29617 (5)	0.05769 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0474 (9)	0.0362 (8)	0.0458 (9)	0.0023 (6)	0.0206 (7)	0.0022 (7)
C2	0.0682 (11)	0.0491 (10)	0.0482 (10)	0.0122 (8)	0.0299 (9)	0.0008 (8)
C3	0.0733 (12)	0.0441 (9)	0.0516 (11)	0.0180 (8)	0.0276 (9)	0.0050 (8)
C4	0.0548 (9)	0.0410 (8)	0.0400 (9)	−0.0083 (7)	0.0195 (8)	0.0006 (7)
C5	0.0521 (9)	0.0390 (8)	0.0384 (9)	−0.0022 (7)	0.0192 (8)	0.0015 (6)
C6	0.0629 (11)	0.0543 (10)	0.0619 (12)	0.0082 (8)	0.0322 (10)	0.0213 (9)
C7	0.0759 (14)	0.1035 (17)	0.0478 (12)	0.0119 (12)	0.0260 (11)	0.0248 (11)
N1	0.0469 (7)	0.0385 (7)	0.0402 (8)	0.0017 (5)	0.0179 (6)	0.0032 (5)
N2	0.0487 (7)	0.0365 (7)	0.0349 (7)	−0.0013 (5)	0.0142 (6)	−0.0012 (5)
O1	0.0616 (7)	0.0491 (7)	0.0443 (7)	−0.0149 (5)	0.0201 (6)	−0.0002 (5)
O2	0.0866 (10)	0.0714 (9)	0.0375 (7)	−0.0274 (7)	0.0232 (7)	0.0024 (6)
Cl1	0.0604 (3)	0.0721 (3)	0.0408 (3)	−0.0079 (2)	0.0194 (2)	0.0024 (2)

Geometric parameters (Å, º)

C1—N1	1.319 (2)	C4—H4A	0.9700
C1—N2	1.330 (2)	C5—O1	1.2005 (19)
C1—H1	0.9300	C5—O2	1.3124 (19)
C2—C3	1.339 (3)	C6—N1	1.474 (2)
C2—N1	1.375 (2)	C6—C7	1.501 (3)
C2—H2A	0.9300	C6—H6A	0.9700
C3—N2	1.370 (2)	C6—H6B	0.9700
C3—H3	0.9300	C7—H7A	0.9600
C4—N2	1.4524 (19)	C7—H7B	0.9600
C4—C5	1.507 (2)	C7—H7C	0.9600
C4—H4B	0.9700	O2—H2	0.96 (3)
N1—C1—N2	108.48 (13)	N1—C6—H6A	109.4
N1—C1—H1	125.8	C7—C6—H6A	109.4
N2—C1—H1	125.8	N1—C6—H6B	109.4
C3—C2—N1	107.16 (15)	C7—C6—H6B	109.4
C3—C2—H2A	126.4	H6A—C6—H6B	108.0
N1—C2—H2A	126.4	C6—C7—H7A	109.5
C2—C3—N2	107.19 (15)	C6—C7—H7B	109.5
C2—C3—H3	126.4	H7A—C7—H7B	109.5
N2—C3—H3	126.4	C6—C7—H7C	109.5
N2—C4—C5	111.49 (13)	H7A—C7—H7C	109.5
N2—C4—H4B	109.3	H7B—C7—H7C	109.5
C5—C4—H4B	109.3	C1—N1—C2	108.62 (13)
N2—C4—H4A	109.3	C1—N1—C6	126.88 (14)
C5—C4—H4A	109.3	C2—N1—C6	124.47 (14)
H4B—C4—H4A	108.0	C1—N2—C3	108.54 (14)
O1—C5—O2	125.37 (16)	C1—N2—C4	125.80 (13)
O1—C5—C4	123.90 (14)	C3—N2—C4	125.46 (14)
O2—C5—C4	110.71 (14)	C5—O2—H2	111.1 (16)
N1—C6—C7	110.98 (16)
N1—C2—C3—N2	0.0 (2)	C7—C6—N1—C2	67.4 (2)
N2—C4—C5—O1	12.9 (2)	N1—C1—N2—C3	0.97 (19)
N2—C4—C5—O2	−168.70 (14)	N1—C1—N2—C4	176.09 (14)
N2—C1—N1—C2	−0.95 (19)	C2—C3—N2—C1	−0.6 (2)
N2—C1—N1—C6	177.42 (15)	C2—C3—N2—C4	−175.75 (15)
C3—C2—N1—C1	0.6 (2)	C5—C4—N2—C1	−85.89 (19)
C3—C2—N1—C6	−177.86 (17)	C5—C4—N2—C3	88.4 (2)
C7—C6—N1—C1	−110.8 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···Cl1	0.93	2.73	3.472 (2)	137
C1—H1···Cl1^i	0.93	2.73	3.5161 (19)	143
C4—H4B···O1^ii	0.97	2.37	3.312 (2)	164
O2—H2···Cl1^iii	0.96 (3)	1.98 (3)	2.9393 (15)	176 (2)
C1—H1···O1^iv	0.93	2.49	3.094 (2)	122
C2—H2A···Cl1^v	0.93	2.84	3.590 (2)	138

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