α-l-Glucose

Takashita, T.; Horii, Y.; Ishii, T.

doi:10.1107/S2414314626008874

organic compounds

IUCrDATA

ISSN: 2414-3146

Volume 11| Part 8| August 2026| x260887

https://doi.org/10.1107/S2414314626008874

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α-L-Glucose

Tomoko Takashita,^a ^* Yoji Horii ^a and Tomohiko Ishii ^a

^aGraduate School of Science for Creative Emergence, Kagawa University, 2217-20 Hayashi-cho, Takamatsu, Kagawa 761-0396, Japan
^*Correspondence e-mail: [email protected]

Edited by L. Van Meervelt, Katholieke Universiteit Leuven, Belgium (Received 21 August 2026; accepted 26 August 2026; online 28 August 2026)

Commercially available L-glucose, C₆H₁₂O₆, was crystallized by slow evaporation from aqueous solution at room temperature affording colorless block-shaped single crystals suitable for single-crystal X-ray diffraction. The title compound crystallizes as α-L-glucose in the orthorhombic space group P2₁2₁2₁, with one molecule in the asymmetric unit and Z = 4. In the crystal, the molecules are linked by O—H⋯O hydrogen bonds, forming a three-dimensional hydrogen-bonded network. This study provides an experimentally determined structural dataset for the rare L enantiomer, which is not currently represented in the Cambridge Structural Database.

Keywords: crystal structure; hydrogen bonding; rare sugar; glucose; monosaccharide.

CCDC reference: 2577717

Structure description

Rare sugars are monosaccharides and derivatives that occur only in limited quantities in nature. The development of systematic bioproduction strategies has facilitated access to a wide range of rare hexoses (Izumori, 2002 ). L-Glucose is a rare sugar and the enantiomer of the naturally occurring D-glucose. The Cambridge Structural Database (CSD, version 6.00, update of August 2025; Groom et al., 2016 ) contains several crystal structures of α-D-glucose, including the neutron-diffraction structures reported by Brown & Levy (1965 , 1979 ; CSD refcodes GLUCSA and GLUCSA10, respectively). In contrast, no experimentally determined crystal structure of α-L-glucose was identified in our CSD search. Although the L enantiomer is expected to be related to the D enantiomer by inversion, its direct experimental determination provides an enantiomer-specific dataset comprising atomic coordinates, molecular conformation and hydrogen-bond geometry. The present structure therefore fills a gap in the crystallographic record and contributes to the systematic accumulation of structural data for rare sugars.

The title compound crystallizes in the orthorhombic space group P2₁2₁2₁. The asymmetric unit contains one molecule of α-L-glucose in the pyranose form (Fig. 1). The pyranose ring adopts a ¹C₄ chair conformation, with the anomeric hydroxy group at C1 occupying an axial position, while the hydroxy groups at C2, C3 and C4 and the hydroxymethyl group at C5 occupy equatorial positions. The Flack parameter of −0.29 (12) was not sufficiently precise to establish the absolute structure independently. The absolute configuration was therefore assigned on the basis of the known identity of the commercially available L-glucose used for crystallization. On this basis, the configurations of the stereogenic centres C1, C2, C3, C4 and C5 are R, S, R, R and S, respectively. The conformation of the hydroxymethyl group is characterized by an O5—C5—C6—O6 torsion angle of −70.7 (3)°. A least-squares fit of the 12 non-hydrogen atoms of the title molecule to those of the α-D-glucose structure reported by Brown & Levy (1965; CSD refcode GLUCSA) gave r.m.s. deviations of 0.910 Å and 0.013 Å without and with inversion, respectively. The very small r.m.s. deviation obtained after inversion indicates that there is no appreciable difference between the molecular conformations of the two enantiomers.

Figure 1
The molecular structure of the title compound, showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms are shown as spheres of arbitrary radius.

In the crystal, each hydroxy group acts as a donor in an O—H⋯O hydrogen bond (Table 1). Collectively, these interactions link the molecules into a three-dimensional hydrogen-bonded network, as shown in Fig. 2.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O5ⁱ	0.95 (4)	1.91 (4)	2.836 (3)	163 (4)
O2—H2⋯O6ⁱⁱ	0.90 (4)	1.87 (4)	2.760 (3)	166 (4)
O3—H3⋯O2ⁱⁱⁱ	0.83 (4)	1.89 (4)	2.698 (3)	165 (3)
O4—H4⋯O4^iv	0.85 (5)	1.93 (5)	2.7625 (17)	165 (5)
O6—H6⋯O3^v	0.84 (4)	1.86 (4)	2.704 (3)	175 (4)
Symmetry codes: (i) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]$ ; (ii) $[-x+{\script{3\over 2}}, -y+1, z+{\script{1\over 2}}]$ ; (iii) $[-x+1, y+{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iv) $[x-{\script{1\over 2}}, -y+{\script{3\over 2}}, -z+1]$ ; (v) $[-x+{\script{1\over 2}}, -y+1, z-{\script{1\over 2}}]$ .

Figure 2
Crystal packing of the title compound viewed along the a axis (projection onto the bc plane), with the b and c unit-cell directions indicated. The central glucose molecule is shown using a ball-and-stick representation, whereas the surrounding molecules are shown using a capped-stick representation. The O1—H1⋯O5, O2—H2⋯O6, O3—H3⋯O2, O4—H4⋯O4 and O6—H6⋯O3 hydrogen bonds listed in Table 1

are shown as dashed lines.

Synthesis and crystallization

Commercially available L-glucose (Sigma–Aldrich) was used as received without further purification. The sample was dissolved in water, and the solution was allowed to evaporate slowly at room temperature. Colorless block-shaped single crystals suitable for single-crystal X-ray diffraction were obtained.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. The Flack parameter was −0.29 (12), determined using 457 quotients (Parsons et al., 2013 ), and did not permit a reliable determination of the absolute structure from the diffraction data alone. The absolute configuration was therefore assigned from the known identity of the commercially available L-glucose used for crystallization.

Table 2
Experimental details

Crystal data
Chemical formula	C₆H₁₂O₆
M_r	180.16
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	296
a, b, c (Å)	4.9536 (4), 10.3185 (7), 14.7798 (11)
V (Å³)	755.45 (9)
Z	4
Radiation type	Cu Kα
μ (mm⁻¹)	1.26
Crystal size (mm)	0.1 × 0.1 × 0.1

Data collection
Diffractometer	Rigaku R-AXIS RAPID
Absorption correction	Multi-scan (ABSCOR; Rigaku, 1995 )
T_min, T_max	0.656, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	8312, 1374, 1271
R_int	0.043
(sin θ/λ)_max (Å⁻¹)	0.602

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.033, 0.076, 1.06
No. of reflections	1374
No. of parameters	133
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.14, −0.16
Absolute structure	Flack x determined using 457 quotients [(I⁺)−(I⁻)]/[(I⁺)+(I⁻)] (Parsons et al., 2013)
Absolute structure parameter	−0.29 (12)
Computer programs: RAPID-AUTO (Rigaku, 2009 ), SHELXT2018/2 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ) and OLEX2 (Dolomanov et al., 2009 ).

Structural data

CCDC reference: 2577717

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2414314626008874/vm4083sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2414314626008874/vm4083Isup2.hkl

checkCIF report

Computing details top

α-L-Glucose top

Crystal data top

C₆H₁₂O₆	D_x = 1.584 Mg m⁻³
M_r = 180.16	Cu Kα radiation, λ = 1.54187 Å
Orthorhombic, P2₁2₁2₁	Cell parameters from 7806 reflections
a = 4.9536 (4) Å	θ = 3.0–68.4°
b = 10.3185 (7) Å	µ = 1.26 mm⁻¹
c = 14.7798 (11) Å	T = 296 K
V = 755.45 (9) Å³	Block, clear light colourless
Z = 4	0.1 × 0.1 × 0.1 mm
F(000) = 384

Data collection top

Rigaku R-AXIS RAPID diffractometer	1271 reflections with I > 2σ(I)
Detector resolution: 10.000 pixels mm^-1	R_int = 0.043
ω scans	θ_max = 68.1°, θ_min = 5.2°
Absorption correction: multi-scan (ABSCOR; Rigaku, 1995)	h = −5→5
T_min = 0.656, T_max = 1.000	k = −12→12
8312 measured reflections	l = −17→17
1374 independent reflections

Refinement top

Refinement on F²	Hydrogen site location: mixed
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F² > 2σ(F²)] = 0.033	w = 1/[σ²(F_o²) + (0.0303P)² + 0.2146P] where P = (F_o² + 2F_c²)/3
wR(F²) = 0.076	(Δ/σ)_max < 0.001
S = 1.06	Δρ_max = 0.14 e Å⁻³
1374 reflections	Δρ_min = −0.15 e Å⁻³
133 parameters	Absolute structure: Flack x determined using 457 quotients [(I⁺)-(I^-)]/[(I⁺)+(I^-)] (Parsons et al., 2013)
0 restraints	Absolute structure parameter: −0.29 (12)
Primary atom site location: dual

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. All non-hydrogen atoms were refined anisotropically. The hydroxy H atoms H1, H2, H3, H4 and H6 and the C-bound H atom H1A were located in difference-Fourier maps and refined freely. The remaining C-bound H atoms were placed in calculated positions and refined using constrained models.

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

	x	y	z	U_iso*/U_eq
O1	0.8530 (4)	0.3471 (2)	0.60082 (14)	0.0418 (6)
H1	0.918 (10)	0.273 (4)	0.570 (3)	0.087 (14)*
O2	0.5651 (5)	0.38741 (19)	0.75979 (12)	0.0377 (5)
H2	0.703 (9)	0.441 (4)	0.774 (3)	0.082 (15)*
O3	0.3351 (5)	0.6328 (2)	0.71548 (13)	0.0412 (6)
H3	0.371 (8)	0.711 (4)	0.713 (2)	0.063 (12)*
O4	0.4329 (5)	0.71765 (18)	0.53468 (13)	0.0344 (5)
H4	0.289 (9)	0.752 (5)	0.514 (3)	0.085 (16)*
O5	0.4615 (4)	0.36546 (16)	0.51522 (11)	0.0302 (5)
O6	0.5544 (5)	0.4462 (2)	0.33123 (14)	0.0454 (6)
H6	0.437 (8)	0.417 (4)	0.295 (2)	0.058 (12)*
C1	0.5752 (6)	0.3328 (3)	0.60101 (17)	0.0295 (6)
H1A	0.526 (4)	0.233 (2)	0.6127 (14)	0.003 (5)*
C2	0.4535 (6)	0.4187 (2)	0.67401 (16)	0.0287 (6)
H2A	0.259784	0.399836	0.676647	0.034*
C3	0.4844 (6)	0.5609 (2)	0.65125 (16)	0.0282 (7)
H3A	0.675258	0.585394	0.654612	0.034*
C4	0.3795 (6)	0.5855 (2)	0.55691 (17)	0.0266 (6)
H4A	0.183949	0.571024	0.556111	0.032*
C5	0.5113 (6)	0.4965 (2)	0.48833 (16)	0.0282 (6)
H5	0.706301	0.512517	0.487074	0.034*
C6	0.3971 (7)	0.5145 (3)	0.39572 (18)	0.0376 (7)
H6A	0.212706	0.482996	0.394260	0.045*
H6B	0.395072	0.606009	0.380678	0.045*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0390 (14)	0.0445 (13)	0.0418 (12)	0.0081 (11)	−0.0048 (10)	−0.0091 (10)
O2	0.0585 (15)	0.0289 (11)	0.0258 (9)	0.0000 (11)	−0.0055 (10)	0.0038 (8)
O3	0.0674 (17)	0.0233 (11)	0.0329 (10)	0.0009 (10)	0.0165 (10)	−0.0026 (8)
O4	0.0400 (13)	0.0247 (10)	0.0385 (11)	−0.0014 (10)	−0.0010 (10)	0.0050 (8)
O5	0.0402 (12)	0.0248 (10)	0.0257 (9)	−0.0023 (9)	−0.0051 (8)	−0.0018 (7)
O6	0.0519 (15)	0.0552 (14)	0.0291 (11)	−0.0086 (13)	0.0052 (11)	−0.0083 (10)
C1	0.0334 (17)	0.0258 (14)	0.0292 (13)	0.0034 (13)	−0.0048 (12)	−0.0006 (11)
C2	0.0356 (17)	0.0241 (14)	0.0264 (13)	0.0001 (13)	−0.0021 (12)	0.0009 (10)
C3	0.0358 (18)	0.0232 (13)	0.0257 (13)	0.0009 (12)	0.0012 (11)	−0.0028 (10)
C4	0.0273 (16)	0.0217 (13)	0.0306 (14)	−0.0023 (11)	0.0008 (11)	0.0028 (10)
C5	0.0288 (17)	0.0274 (14)	0.0285 (13)	−0.0025 (11)	−0.0024 (11)	−0.0008 (10)
C6	0.0444 (19)	0.0399 (17)	0.0284 (14)	0.0009 (15)	−0.0005 (13)	−0.0009 (12)

Geometric parameters (Å, º) top

O1—H1	0.95 (4)	C1—H1A	1.07 (2)
O1—C1	1.384 (4)	C1—C2	1.521 (4)
O2—H2	0.90 (4)	C2—H2A	0.9800
O2—C2	1.420 (3)	C2—C3	1.513 (4)
O3—H3	0.83 (4)	C3—H3A	0.9800
O3—C3	1.413 (3)	C3—C4	1.509 (3)
O4—H4	0.85 (5)	C4—H4A	0.9800
O4—C4	1.428 (3)	C4—C5	1.516 (3)
O5—C1	1.428 (3)	C5—H5	0.9800
O5—C5	1.430 (3)	C5—C6	1.493 (3)
O6—H6	0.84 (4)	C6—H6A	0.9700
O6—C6	1.419 (4)	C6—H6B	0.9700

C1—O1—H1	105 (3)	C2—C3—H3A	109.6
C2—O2—H2	111 (3)	C4—C3—C2	109.5 (2)
C3—O3—H3	111 (3)	C4—C3—H3A	109.6
C4—O4—H4	109 (3)	O4—C4—C3	108.0 (2)
C1—O5—C5	113.68 (19)	O4—C4—H4A	109.0
C6—O6—H6	103 (3)	O4—C4—C5	110.2 (2)
O1—C1—O5	111.4 (2)	C3—C4—H4A	109.0
O1—C1—H1A	109.2 (12)	C3—C4—C5	111.6 (2)
O1—C1—C2	109.5 (2)	C5—C4—H4A	109.0
O5—C1—H1A	106.2 (11)	O5—C5—C4	108.2 (2)
O5—C1—C2	109.7 (2)	O5—C5—H5	109.6
C2—C1—H1A	110.8 (12)	O5—C5—C6	107.9 (2)
O2—C2—C1	110.3 (2)	C4—C5—H5	109.6
O2—C2—H2A	107.5	C6—C5—C4	112.0 (2)
O2—C2—C3	112.3 (2)	C6—C5—H5	109.6
C1—C2—H2A	107.5	O6—C6—C5	110.2 (3)
C3—C2—C1	111.6 (2)	O6—C6—H6A	109.6
C3—C2—H2A	107.5	O6—C6—H6B	109.6
O3—C3—C2	107.9 (2)	C5—C6—H6A	109.6
O3—C3—H3A	109.6	C5—C6—H6B	109.6
O3—C3—C4	110.6 (2)	H6A—C6—H6B	108.1

O1—C1—C2—O2	−57.4 (3)	C1—O5—C5—C4	−62.1 (3)
O1—C1—C2—C3	68.1 (3)	C1—O5—C5—C6	176.5 (2)
O2—C2—C3—O3	−63.5 (3)	C1—C2—C3—O3	172.1 (2)
O2—C2—C3—C4	176.1 (2)	C1—C2—C3—C4	51.7 (3)
O3—C3—C4—O4	66.2 (3)	C2—C3—C4—O4	−175.0 (2)
O3—C3—C4—C5	−172.5 (2)	C2—C3—C4—C5	−53.8 (3)
O4—C4—C5—O5	177.8 (2)	C3—C4—C5—O5	57.8 (3)
O4—C4—C5—C6	−63.4 (3)	C3—C4—C5—C6	176.6 (2)
O5—C1—C2—O2	−179.9 (2)	C4—C5—C6—O6	170.3 (2)
O5—C1—C2—C3	−54.4 (3)	C5—O5—C1—O1	−60.5 (3)
O5—C5—C6—O6	−70.7 (3)	C5—O5—C1—C2	60.8 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O5ⁱ	0.95 (4)	1.91 (4)	2.836 (3)	163 (4)
O2—H2···O6ⁱⁱ	0.90 (4)	1.87 (4)	2.760 (3)	166 (4)
O3—H3···O2ⁱⁱⁱ	0.83 (4)	1.89 (4)	2.698 (3)	165 (3)
O4—H4···O4^iv	0.85 (5)	1.93 (5)	2.7625 (17)	165 (5)
O6—H6···O3^v	0.84 (4)	1.86 (4)	2.704 (3)	175 (4)

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

Acknowledgements

The authors thank Professor Genta Sakane (Okayama University of Science) for constructive discussions and technical guidance, and Kei Takeshita (FUSHIMI Pharmaceutical Co., Ltd.) for helpful advice. The authors also acknowledge support from the JST Support for Pioneering Research Initiated by the Next Generation (SPRING) program.

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