Structure of the inclusion complex of β-cyclodextrin with lipoic acid from laboratory powder diffraction data

The crystal structure of the inclusion complex of β-cyclodextrin with lipoic acid was determined from laboratory powder diffraction data. Thermogravimetric data was used to estimate the number of water molecules in the crystal structure. Lipoic acid is included in β-cyclodextrin through its primary face with the five-membered ring reaching the center plane of the cyclodextrin cavity and its fatty acid chain adopting a bent conformation. Lipoic acid and β-cyclodextrin form a channel-like packing which is stabilized by guest–host hydrogen bonding and close contacts, host–host intermolecular interactions and hydrogen bonding involving the water molecules.

Computing details

Program(s) used to refine structure: GSAS.

(LIP)

Crystal data

C42O35·C8O2S2·O9	β = 110.5195°
Mr = 700.31	V = 6812.18 Å^3
Monoclinic, C2	Z = 8
a = 18.8929 Å	Cu Kα radiation, λ = 1.5405 Å
b = 24.4634 Å	T = 295 K
c = 15.7376 Å	?, ? × ? × ? mm

Data collection

Bruker D8 Advanced diffractometer	Data collection mode: reflection
Radiation source: CuKα, 2.2kW Cu anode long fine focus ceramic X-ray tube	Scan method: step
Ge 111 crystal monochromator	2θmin = 2.999°, 2θmax = 49.979°, 2θstep = 0.01°
Specimen mounting: plate holder

Refinement

Least-squares matrix: full	4699 data points
Rp = 0.092	Profile function: CW Profile function number 5 with 17 terms Profile function not installed. This is an error & should not happen! Peak tails are ignored where the intensity is below 0.0100 times the peak Aniso. broadening axis 0.0 0.0 1.0
Rwp = 0.128	167 parameters
Rexp = 0.033	141 restraints
R(F^2) = 0.12487	(Δ/σ)max = 0.05
χ^2 = 30.581	Background function: GSAS Background function number 1 with 18 terms. Shifted Chebyshev function of 1st kind 1: 528.134 2: -517.062 3: 167.079 4: -86.8962 5: 62.7871 6: -26.5990 7: 26.6140 8: 16.8098 9: -17.0629 10: -6.71591 11: 23.5081 12: 4.96859 13: 20.7329 14: -1.06822 15: -8.52721 16: -5.28689 17: 14.5610 18: -7.76431

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

	x	y	z	Uiso*/Ueq
O41	1.0686 (4)	0.4207 (7)	0.7932 (5)	0.02219*
C11	1.1162 (5)	0.4148 (9)	0.7415 (8)	0.02547*
C21	1.1936 (5)	0.4204 (10)	0.8165 (9)	0.02547*
C31	1.2103 (6)	0.4793 (10)	0.8490 (9)	0.02547*
C41	1.2002 (6)	0.5166 (10)	0.7672 (10)	0.02547*
C51	1.1214 (6)	0.5073 (9)	0.6951 (9)	0.02547*
O21	1.1964 (5)	0.3867 (10)	0.8900 (8)	0.02219*
O31	1.2853 (6)	0.4828 (10)	0.9092 (10)	0.02219*
O51	1.1097 (5)	0.4515 (9)	0.6703 (9)	0.02219*
O61	1.1787 (4)	0.5504 (3)	0.594 (3)	0.02219*
C61	1.1111 (4)	0.5452 (3)	0.6109 (15)	0.02547*
O42	1.2652 (6)	0.5404 (4)	0.7544 (10)	0.02219*
C12	1.2772 (3)	0.5984 (4)	0.7604 (9)	0.02547*
C22	1.3087 (4)	0.6336 (4)	0.8455 (9)	0.02547*
C32	1.2511 (4)	0.6762 (4)	0.8499 (9)	0.02547*
C42	1.2263 (4)	0.7103 (4)	0.7626 (9)	0.02547*
C52	1.2003 (4)	0.6725 (4)	0.6792 (9)	0.02547*
O22	1.3287 (4)	0.5999 (4)	0.9226 (9)	0.02219*
O32	1.2851 (4)	0.7105 (4)	0.9246 (9)	0.02219*
O52	1.2540 (3)	0.6314 (4)	0.6820 (9)	0.02219*
O62	1.1889 (12)	0.7606 (2)	0.5908 (7)	0.02219*
C62	1.191 (2)	0.7034 (2)	0.5885 (15)	0.02547*
O43	1.2482 (5)	0.7654 (2)	0.7594 (6)	0.02219*
C13	1.1854 (4)	0.7978 (4)	0.7589 (7)	0.02547*
C23	1.1713 (4)	0.8257 (4)	0.8384 (7)	0.02547*
C33	1.0925 (4)	0.8123 (4)	0.8390 (7)	0.02547*
C43	1.0341 (4)	0.8295 (4)	0.7476 (6)	0.02547*
C53	1.0531 (4)	0.8013 (4)	0.6707 (7)	0.02547*
O23	1.2259 (4)	0.8086 (4)	0.9203 (7)	0.02219*
O33	1.0808 (4)	0.8421 (4)	0.9092 (7)	0.02219*
O53	1.1284 (4)	0.8118 (4)	0.6763 (7)	0.02219*
O63	1.0421 (9)	0.8815 (11)	0.5793 (10)	0.02219*
C63	1.0097 (5)	0.8299 (4)	0.5822 (2)	0.02547*
O44	0.9578 (6)	0.8104 (6)	0.7301 (16)	0.02219*
C14	0.8945 (5)	0.8479 (6)	0.6994 (12)	0.02547*
C24	0.8610 (5)	0.8477 (6)	0.7749 (12)	0.02547*
C34	0.8238 (5)	0.7931 (6)	0.7801 (11)	0.02547*
C44	0.7644 (5)	0.7806 (6)	0.6868 (10)	0.02547*
C54	0.8032 (5)	0.7816 (6)	0.6156 (11)	0.02547*
O24	0.9182 (6)	0.8587 (6)	0.8583 (12)	0.02219*
O34	0.7893 (5)	0.7970 (6)	0.8459 (11)	0.02219*
O54	0.8400 (5)	0.8321 (6)	0.6158 (12)	0.02219*
O64	0.6677 (9)	0.7788 (11)	0.5044 (11)	0.02219*
C64	0.7468 (8)	0.7634 (12)	0.5206 (11)	0.02547*
O45	0.6856 (3)	0.7877 (5)	0.6651 (9)	0.02219*
C15	0.6423 (8)	0.7392 (5)	0.6550 (10)	0.02547*
C25	0.6165 (8)	0.7152 (5)	0.7289 (10)	0.02547*
C35	0.6507 (8)	0.6587 (5)	0.7581 (9)	0.02547*
C45	0.6350 (7)	0.6216 (5)	0.6750 (9)	0.02547*
C55	0.6562 (7)	0.6503 (5)	0.6001 (10)	0.02547*
O25	0.6377 (9)	0.7511 (5)	0.8033 (10)	0.02219*
O35	0.6183 (8)	0.6359 (5)	0.8180 (9)	0.02219*
O55	0.6243 (7)	0.7032 (5)	0.5806 (10)	0.02219*
O65	0.5818 (13)	0.5810 (13)	0.486 (2)	0.02219*
C65	0.6431 (9)	0.6200 (11)	0.5070 (14)	0.02547*
O46	0.6637 (6)	0.5669 (3)	0.7021 (8)	0.02219*
C16	0.6138 (6)	0.5260 (7)	0.7117 (11)	0.02546*
C26	0.6559 (6)	0.5025 (7)	0.8058 (10)	0.02547*
C36	0.7352 (6)	0.4841 (8)	0.8145 (10)	0.02547*
C46	0.7299 (5)	0.4433 (7)	0.7386 (10)	0.02547*
C56	0.6834 (5)	0.4684 (7)	0.6461 (10)	0.02547*
O26	0.6611 (7)	0.5424 (8)	0.8718 (11)	0.02219*
O36	0.7687 (6)	0.4584 (8)	0.8989 (10)	0.02219*
O56	0.6120 (6)	0.4879 (6)	0.6437 (10)	0.02219*
O66	0.73114 (18)	0.39733 (15)	0.5740 (11)	0.02219*
C66	0.67327 (18)	0.43584 (15)	0.5595 (10)	0.02547*
O47	0.8060 (5)	0.4397 (5)	0.7464 (9)	0.02219*
C17	0.8329 (5)	0.3858 (7)	0.7521 (8)	0.02547*
C27	0.9006 (5)	0.3680 (8)	0.8400 (8)	0.02547*
C37	0.9727 (5)	0.4008 (8)	0.8544 (8)	0.02547*
C47	0.9956 (5)	0.3947 (8)	0.7704 (8)	0.02547*
C57	0.9287 (5)	0.4123 (7)	0.6859 (8)	0.02547*
O27	0.8773 (5)	0.3760 (8)	0.9146 (7)	0.02219*
O37	1.0305 (5)	0.3800 (8)	0.9307 (8)	0.02219*
O57	0.8624 (4)	0.3826 (7)	0.6781 (8)	0.02219*
O67	0.931 (3)	0.3582 (10)	0.545 (3)	0.02219*
C67	0.9464 (15)	0.4094 (10)	0.5953 (12)	0.02547*
S1	1.0081 (12)	0.6430 (16)	0.7515 (11)	0.00991*
S2	0.9349 (10)	0.5824 (14)	0.7507 (8)	0.00991*
C2	0.9448 (9)	0.6012 (15)	0.5852 (10)	0.02547*
C1	0.9731 (13)	0.6570 (15)	0.6299 (11)	0.02547*
C3	0.8920 (9)	0.5731 (13)	0.6279 (7)	0.02547*
C4	0.8874 (11)	0.5101 (9)	0.610 (3)	0.02547*
C5	0.8090 (12)	0.4828 (15)	0.596 (2)	0.02547*
C6	0.7641 (10)	0.4749 (9)	0.4936 (14)	0.02547*
C7	0.6938 (14)	0.5120 (12)	0.4571 (15)	0.02547*
C8	0.672 (2)	0.5199 (7)	0.3525 (11)	0.02547*
O2	0.6518 (15)	0.4829 (9)	0.2959 (16)	0.02219*
O1	0.6504 (11)	0.5698 (8)	0.3332 (14)	0.02219*
O90	0.0560 (7)	0.0855 (10)	−0.0914 (12)	0.02219*
O91	0.4351 (15)	0.0833 (14)	−0.109 (3)	0.02219*
O92	0.0191 (15)	−0.0793 (10)	0.217 (2)	0.02219*
O93	0.489 (3)	0.732 (3)	−0.196 (4)	0.02219*
O94	0.1481 (8)	0.3108 (7)	−0.0406 (14)	0.02219*
O95	0.1696 (15)	0.6454 (14)	0.121 (4)	0.02219*
O96	0.0626 (5)	0.2421 (7)	−0.0091 (12)	0.02219*
O97	0.2791 (14)	0.6415 (12)	0.0346 (12)	0.02219*
O98	−0.0332 (12)	0.2548 (14)	0.546 (2)	0.02219*