Crystal structure of 1-[(4-methylbenzene)sulfonyl]pyrrolidine

Stenfors, B.A.; Staples, R.J.; Biros, S.M.; Ngassa, F.N.

doi:10.1107/S205698902000208X

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Volume 76| Part 3| March 2020| Pages 452-455

https://doi.org/10.1107/S205698902000208X

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Crystal structure of 1-[(4-methylbenzene)sulfonyl]pyrrolidine

Brock A. Stenfors,^a Richard J. Staples,^b Shannon M. Biros ^a and Felix N. Ngassa ^a ^*

^aDepartment of Chemistry, 1 Campus Dr., Grand Valley State University, Allendale, MI 49401, USA, and ^bCenter for Crystallographic Research, Michigan State University, Department of Chemistry and Chemical Biology, East Lansing, MI 48824, USA
^*Correspondence e-mail: ngassaf@gvsu.edu

Edited by M. Weil, Vienna University of Technology, Austria (Received 22 January 2020; accepted 13 February 2020; online 28 February 2020)

The molecular structure of the title compound, C₁₁H₁₅NO₂S, features a sulfonamide group with S=O bond lengths of 1.4357 (16) and 1.4349 (16) Å, an S—N bond length of 1.625 (2) Å, and an S—C bond length of 1.770 (2) Å. When viewing the molecule down the S—N bond, both N—C bonds of the pyrrolidine ring are oriented gauche to the S—C bond with torsion angles of −65.6 (2)° and 76.2 (2)°. The crystal structure features both intra- and intermolecular C—H⋯O hydrogen bonds, as well as intermolecular C—H⋯π and π–π interactions, leading to the formation of sheets parallel to the ac plane.

Keywords: crystal structure; sulfonamide; π–π interaction; C—H⋯O hydrogen bonds; C—H⋯π interactions; polymorphism.

CCDC reference: 1983920

1. Chemical context

Sulfonamides are of significant value in organic chemistry because of their therapeutic properties. These molecules are referred to in the pharmaceutical industry as sulfa drugs. This class of drugs has been widely used in various pharmaceutical applications owing to their antibacterial, antiviral, antimalarial, antifungal, anticancer, antidepressant, and other properties (Apaydın & Török, 2019 ).

N-containing heterocycles have found many uses in pharmaceutical and materials sciences, and as a result they have attracted the attention of many in the synthetic community. Numerous synthetic methods leading to N-containing heterocycles have been reported (Jiang & Ma, 2013 ). Notwithstanding, because of the importance of N-containing heterocycles, new and versatile synthetic methods are still desirable. The pyrrolidine-4-methylbenzenesulfonamide moiety is found in a variety of biologically important compounds that exhibit anti-inflammatory properties. L-proline-derived 4-methylbenzenesulfonamides (Fig. 1) have been reported to exhibit anti-inflammatory activity against Trypanosoma brucei gambiense (Ugwu et al., 2018 ). Furthermore, these compounds can permeate the blood-brain barrier and hence can be used in treating inflammation of the brain (Ugwu et al., 2017 ).

Figure 1
L-proline-derived 4-methylbenzenesulfonamide compounds that have been reported to exhibit anti-inflammatory activity against (a) Trypanosoma brucei gambiense and (b) to reduce brain inflammation.

Generally, sulfonamides are synthesized by an analogous nucleophilic acyl-substitution reaction between an electrophile and a nucleophilic amine (Patel et al., 2018 ). Efficient methods from the literature involve the base-catalyzed sulfonylation of amines using sulfonyl halides (Yan et al., 2007 ) or sulfonic acids (De Luca & Giacomelli, 2008 ) as electrophiles. The title compound, along with some related analogs, has been synthesized previously (Ohwada, et al., 1998 ). Recently, we have discovered a more efficient method using aqueous potassium carbonate as the base. This method avoids the use of a phase-transfer catalyst by using tetrahydrofuran as a water-miscible solvent. An increased rate of reaction and yield of sulfonamide compounds produced from a wide range of amines has been observed. These reaction conditions produced the title compound in a 91% yield, compared to the 58% yield previously reported.

In a continuation of our research group's ongoing interest in synthesizing small sulfonamide molecules that mimic the structural motifs of known sulfonamide drug candidates, we synthesized the title compound, C₁₁H₁₅NO₂S, and determined its crystal structure from single-crystal X-ray diffraction data.

2. Structural commentary

The molecular structure of the title compound is shown in Fig. 2. The S1=O1 and S1=O2 bond lengths are 1.4357 (16) and 1.4349 (16) Å, which is in line with known values. The S1—C5 and S1—N1 bond lengths are 1.770 (2) and 1.625 (2) Å, respectively, with an N1—S1—C5 bond angle of 107.66 (9)°. The τ₄ descriptor for fourfold coordination around the sulfur atom, S1, is 0.94, indicating a slightly distorted tetrahedron (ideal values are 0 for square-planar, 0.85 for trigonal–pyramidal, and 1 for tetrahedral coordination; Yang et al., 2007 ). Both C—N bonds of the pyrrolidine ring are oriented gauche to the S1—C5 bond with torsion angles C5—S1—N1—C1 = −65.62 (18)° and C5—S1—N1—C4 = 76.16 (19)°. A conformational analysis of the five-membered pyrrolidine ring pucker gives a puckering amplitude (Q₂) parameter of 0.352 (3) Å and a φ₂ parameter of 262.2 (4)°. Consequently, this ring is in a half-chair conformation with a twist along the C2—C3 bond. Lastly, an intramolecular C—H⋯O contact (Sutor, 1958 ,1962 ,1963 ; Steiner, 1996 ) is present between H10 and O2 with an H⋯A distance of 2.54 Å (Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

Cg2 is the centroid of the C5–C10 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯O1ⁱ	0.95	2.46	3.406 (3)	174
C10—H10⋯O2	0.95	2.54	2.917 (3)	104
C11—H11C⋯Cg2ⁱⁱ	0.98	2.73	3.614 (3)	150
Symmetry codes: (i) -x+1, -y+1, -z; (ii) -x, -y+1, -z+1.

Figure 2
The molecular structure of the title compound, with the atom-labeling scheme. Displacement ellipsoids are drawn at the 40% probability level, and all hydrogen atoms have been omitted for clarity.

3. Supramolecular features

In the crystal structure of the title compound, molecules are linked by π–π interactions, C—H⋯O hydrogen bonds, and C—H⋯π interactions (Fig. 3, Table 1). The C—H⋯O hydrogen bond is formed between an aromatic C—H group (C6—H6) and one of the sulfonamide O atoms (O1). The C—H⋯π interaction is between the methyl group (C11—H11C) and a symmetry-derived ring (C5–C10; symmetry code: –x, –y + 1, –z + 1). The π–π interaction has a centroid-to-centroid distance of 3.8162 (15) Å with a slippage of 1.307 Å. The result of these interactions is the formation of sheets that lie in the ac plane (Fig. 4).

Figure 3
A depiction of the non-covalent interactions present in the crystal of the title compound using a ball-and-stick model with standard CPK colors. C—H⋯O hydrogen bonds and C—H⋯π interactions are shown with purple dashed lines, and π–π interactions are shown with magenta dashed lines. For clarity, most hydrogen atoms have been omitted and only one orientation of the intramolecular C—H⋯O hydrogen bond is shown. [Symmetry codes: (i) −x, 1 − y, 1 − z; (ii) 1 − x, 1 − y, −z; (iii) 1 − x, 1 − y, 1 − z.]

Figure 4
A view down the a axis of the crystal packing showing the supramolecular sheets formed via non-covalent interactions. C—H⋯O hydrogen bonds and C—H⋯π interactions are shown with purple dashed lines, and π–π interactions are shown with magenta dashed lines. For clarity, only those hydrogen atoms involved in a non-covalent interaction are shown, along with H11A and H11B.

4. Database survey

The Cambridge Structural Database (CSD, Version 5.40, August 2019; Groom et al., 2016 ) contains hundreds of structures that comprise a p-toluenesulfonamide group bearing a pyrrolidine ring. Included in this list is another crystal-structure determination of the title compound (refcode: BABLEV; Ohwada et al., 1998), which also crystallizes in the P $[\overline{1}]$ space group. Unfortunately, coordinates were not deposited for this structure at that time, so we are unable to say whether the title compound is a new packing polymorph or a new conformational polymorph. The reduced cell of BABLEV is a = 8.241, b = 2.671, c = 9.240 Å, α = 76.550, β = 63.800, γ = 87.880° with a volume of 574.55 Å³. The theoretical X-ray density values for each structure are similar, with 1.30 g cm⁻³ for BABLEV and 1.36 g cm⁻³ for the title compound. Thus, the more densely packed structure reported here is likely the more thermodynamically stable form.

A selection of other structures in the CSD that are closely related to the title compound are BOKPEX (Rao & Chan, 2008 ), GAWDAK (Chen et al., 2005 ), VECTUT (Sherman et al., 2007 ) and YIRCOS (Wang & Peng, 2008 ). These structures were chosen for comparison because they have relatively simple substituents on the pyrrolidine ring. In their paper describing the structure of GAWDAK, the authors report that this crystal also features both intra- and intermolecular hydrogen bonds in the solid state.

5. Synthesis and crystallization

The title compound was prepared by the dropwise addition of p-toluenesulfonyl chloride (1.00 g, 5.25 mmol) to a stirring mixture of pyrrolidine (0.48 ml, 5.90 mmol) and 10 ml of tetrahydrofuran. This was followed by the dropwise addition of 0.59 M aqueous potassium carbonate (10 ml, 5.90 mmol) and the mixture was stirred at room temperate for 6 h. Upon acidification with 5 M HCl, a white precipitate was isolated by vacuum filtration to give the crude sulfonamide product. The crude product was dissolved in hot ethanol and filtered. The filtrate was transferred to a scintillation vial and crystallized upon standing for 24 h to afford colorless crystals, filtered from the mother liquor (yield 91%; m.p. 405–407 K).

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms bonded to carbon atoms were placed in calculated positions and refined as riding: C—H = 0.95–1.00 Å with U_iso(H) = 1.2U_eq(C) for methylene groups and aromatic hydrogen atoms, and U_iso(H) = 1.5U_eq(C) for methyl groups.

Table 2
Experimental details

Crystal data
Chemical formula	C₁₁H₁₅NO₂S
M_r	225.30
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	173
a, b, c (Å)	7.5347 (1), 8.2581 (1), 9.6157 (1)
α, β, γ (°)	77.876 (1), 86.132 (1), 69.682 (1)
V (Å³)	548.56 (1)
Z	2
Radiation type	Cu Kα
μ (mm⁻¹)	2.46
Crystal size (mm)	0.22 × 0.16 × 0.04

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.631, 0.753
No. of measured, independent and observed [I > 2σ(I)] reflections	7120, 1944, 1715
R_int	0.033
(sin θ/λ)_max (Å⁻¹)	0.603

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.041, 0.120, 1.09
No. of reflections	1944
No. of parameters	137
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.53, −0.33
Computer programs: APEX2 and SAINT (Bruker, 2013 ), SHELXT (Sheldrick, 2015 ), OLEX2 (Dolomanov et al., 2009 ; Bourhis et al., 2015 ) and CrystalMaker (Palmer, 2007 ).

Supporting information

CCDC reference: 1983920

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S205698902000208X/wm5540sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S205698902000208X/wm5540Isup2.hkl

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2013); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: ShelXT (Sheldrick, 2015); program(s) used to refine structure: OLEX2 (Dolomanov et al., 2009; Bourhis et al., 2015); molecular graphics: OLEX2 (Dolomanov et al., 2009; Bourhis et al., 2015); software used to prepare material for publication: CrystalMaker (Palmer, 2007).

1-[(4-Methylbenzene)sulfonyl]pyrrolidine top

Crystal data top

C₁₁H₁₅NO₂S	Z = 2
M_r = 225.30	F(000) = 240
Triclinic, P1	D_x = 1.364 Mg m⁻³
a = 7.5347 (1) Å	Cu Kα radiation, λ = 1.54178 Å
b = 8.2581 (1) Å	Cell parameters from 3988 reflections
c = 9.6157 (1) Å	θ = 4.7–68.2°
α = 77.876 (1)°	µ = 2.46 mm⁻¹
β = 86.132 (1)°	T = 173 K
γ = 69.682 (1)°	Plate, colourless
V = 548.56 (1) Å³	0.22 × 0.16 × 0.04 mm

Data collection top

Bruker APEXII CCD diffractometer	1715 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.033
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θ_max = 68.3°, θ_min = 4.7°
T_min = 0.631, T_max = 0.753	h = −9→9
7120 measured reflections	k = −9→9
1944 independent reflections	l = −11→11

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.041	H-atom parameters constrained
wR(F²) = 0.120	w = 1/[σ²(F_o²) + (0.0698P)² + 0.2666P] where P = (F_o² + 2F_c²)/3
S = 1.09	(Δ/σ)_max < 0.001
1944 reflections	Δρ_max = 0.53 e Å⁻³
137 parameters	Δρ_min = −0.33 e Å⁻³
0 restraints

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.

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

	x	y	z	U_iso*/U_eq
S1	0.56522 (7)	0.19952 (7)	0.20258 (5)	0.0225 (2)
O1	0.6545 (2)	0.2957 (2)	0.09657 (16)	0.0302 (4)
O2	0.6789 (2)	0.0403 (2)	0.29321 (17)	0.0313 (4)
N1	0.4193 (3)	0.1465 (2)	0.11936 (19)	0.0239 (4)
C1	0.3110 (3)	0.0415 (3)	0.2046 (2)	0.0283 (5)
H1A	0.263738	0.084458	0.293341	0.034*
H1B	0.389620	−0.084784	0.228939	0.034*
C2	0.1485 (3)	0.0702 (3)	0.1065 (3)	0.0353 (6)
H2A	0.184331	−0.016766	0.043620	0.042*
H2B	0.035011	0.061924	0.161429	0.042*
C3	0.1137 (4)	0.2554 (4)	0.0214 (4)	0.0511 (8)
H3A	0.051601	0.272209	−0.070616	0.061*
H3B	0.032278	0.344031	0.074899	0.061*
C4	0.3053 (4)	0.2719 (3)	−0.0018 (3)	0.0357 (6)
H4A	0.359019	0.240275	−0.093216	0.043*
H4B	0.299424	0.393584	−0.001822	0.043*
C5	0.4298 (3)	0.3438 (3)	0.3132 (2)	0.0225 (5)
C6	0.3318 (3)	0.5190 (3)	0.2538 (2)	0.0287 (5)
H6	0.342164	0.563001	0.155156	0.034*
C7	0.2192 (3)	0.6284 (3)	0.3400 (3)	0.0331 (6)
H7	0.149316	0.747265	0.299159	0.040*
C8	0.2063 (3)	0.5674 (4)	0.4859 (3)	0.0334 (6)
C9	0.3052 (4)	0.3933 (4)	0.5423 (3)	0.0359 (6)
H9	0.296907	0.349698	0.641258	0.043*
C10	0.4167 (3)	0.2805 (3)	0.4575 (2)	0.0296 (5)
H10	0.483503	0.160696	0.497955	0.035*
C11	0.0852 (4)	0.6900 (4)	0.5788 (3)	0.0516 (8)
H11A	0.096515	0.806829	0.547317	0.077*
H11B	0.127699	0.643344	0.677852	0.077*
H11C	−0.047268	0.699432	0.571301	0.077*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
S1	0.0196 (3)	0.0255 (3)	0.0225 (3)	−0.0078 (2)	−0.00028 (19)	−0.0042 (2)
O1	0.0262 (8)	0.0370 (10)	0.0289 (9)	−0.0143 (7)	0.0064 (6)	−0.0056 (7)
O2	0.0243 (8)	0.0313 (9)	0.0345 (9)	−0.0062 (7)	−0.0048 (7)	−0.0023 (7)
N1	0.0240 (9)	0.0269 (10)	0.0223 (9)	−0.0101 (8)	−0.0003 (7)	−0.0057 (7)
C1	0.0278 (11)	0.0262 (12)	0.0327 (12)	−0.0117 (9)	−0.0001 (9)	−0.0051 (9)
C2	0.0280 (12)	0.0392 (15)	0.0423 (15)	−0.0142 (10)	−0.0049 (10)	−0.0095 (11)
C3	0.0361 (15)	0.0509 (18)	0.0596 (19)	−0.0150 (13)	−0.0176 (13)	0.0090 (14)
C4	0.0395 (14)	0.0379 (14)	0.0281 (13)	−0.0140 (11)	−0.0081 (10)	0.0005 (10)
C5	0.0217 (10)	0.0269 (12)	0.0224 (11)	−0.0113 (9)	−0.0004 (8)	−0.0069 (8)
C6	0.0318 (12)	0.0295 (13)	0.0267 (12)	−0.0141 (10)	0.0011 (9)	−0.0039 (9)
C7	0.0316 (12)	0.0262 (13)	0.0443 (15)	−0.0114 (10)	0.0041 (10)	−0.0118 (10)
C8	0.0288 (12)	0.0453 (15)	0.0383 (14)	−0.0212 (11)	0.0072 (10)	−0.0215 (11)
C9	0.0370 (13)	0.0553 (17)	0.0224 (12)	−0.0224 (12)	0.0024 (10)	−0.0119 (11)
C10	0.0302 (12)	0.0361 (14)	0.0225 (11)	−0.0122 (10)	−0.0032 (9)	−0.0035 (9)
C11	0.0418 (15)	0.070 (2)	0.0624 (19)	−0.0267 (15)	0.0161 (14)	−0.0471 (17)

Geometric parameters (Å, º) top

S1—O1	1.4357 (16)	C4—H4B	0.9900
S1—O2	1.4349 (16)	C5—C6	1.390 (3)
S1—N1	1.6248 (18)	C5—C10	1.386 (3)
S1—C5	1.770 (2)	C6—H6	0.9500
N1—C1	1.481 (3)	C6—C7	1.382 (3)
N1—C4	1.476 (3)	C7—H7	0.9500
C1—H1A	0.9900	C7—C8	1.397 (4)
C1—H1B	0.9900	C8—C9	1.379 (4)
C1—C2	1.518 (3)	C8—C11	1.511 (3)
C2—H2A	0.9900	C9—H9	0.9500
C2—H2B	0.9900	C9—C10	1.386 (3)
C2—C3	1.517 (4)	C10—H10	0.9500
C3—H3A	0.9900	C11—H11A	0.9800
C3—H3B	0.9900	C11—H11B	0.9800
C3—C4	1.495 (4)	C11—H11C	0.9800
C4—H4A	0.9900

O1—S1—N1	106.88 (9)	N1—C4—H4B	110.9
O1—S1—C5	108.04 (10)	C3—C4—H4A	110.9
O2—S1—O1	119.67 (10)	C3—C4—H4B	110.9
O2—S1—N1	106.48 (10)	H4A—C4—H4B	108.9
O2—S1—C5	107.59 (10)	C6—C5—S1	119.68 (17)
N1—S1—C5	107.66 (9)	C10—C5—S1	120.00 (18)
C1—N1—S1	118.02 (14)	C10—C5—C6	120.3 (2)
C4—N1—S1	120.69 (16)	C5—C6—H6	120.4
C4—N1—C1	110.89 (17)	C7—C6—C5	119.2 (2)
N1—C1—H1A	111.1	C7—C6—H6	120.4
N1—C1—H1B	111.1	C6—C7—H7	119.4
N1—C1—C2	103.35 (18)	C6—C7—C8	121.3 (2)
H1A—C1—H1B	109.1	C8—C7—H7	119.4
C2—C1—H1A	111.1	C7—C8—C11	120.4 (3)
C2—C1—H1B	111.1	C9—C8—C7	118.4 (2)
C1—C2—H2A	111.1	C9—C8—C11	121.2 (3)
C1—C2—H2B	111.1	C8—C9—H9	119.3
H2A—C2—H2B	109.1	C8—C9—C10	121.3 (2)
C3—C2—C1	103.2 (2)	C10—C9—H9	119.3
C3—C2—H2A	111.1	C5—C10—C9	119.5 (2)
C3—C2—H2B	111.1	C5—C10—H10	120.2
C2—C3—H3A	110.7	C9—C10—H10	120.2
C2—C3—H3B	110.7	C8—C11—H11A	109.5
H3A—C3—H3B	108.8	C8—C11—H11B	109.5
C4—C3—C2	105.2 (2)	C8—C11—H11C	109.5
C4—C3—H3A	110.7	H11A—C11—H11B	109.5
C4—C3—H3B	110.7	H11A—C11—H11C	109.5
N1—C4—C3	104.3 (2)	H11B—C11—H11C	109.5
N1—C4—H4A	110.9

S1—N1—C1—C2	161.32 (16)	C1—N1—C4—C3	6.5 (3)
S1—N1—C4—C3	−137.8 (2)	C1—C2—C3—C4	36.6 (3)
S1—C5—C6—C7	176.88 (17)	C2—C3—C4—N1	−26.6 (3)
S1—C5—C10—C9	−177.89 (17)	C4—N1—C1—C2	16.0 (2)
O1—S1—N1—C1	178.52 (15)	C5—S1—N1—C1	−65.62 (18)
O1—S1—N1—C4	−39.71 (19)	C5—S1—N1—C4	76.16 (19)
O1—S1—C5—C6	38.27 (19)	C5—C6—C7—C8	1.8 (3)
O1—S1—C5—C10	−143.93 (18)	C6—C5—C10—C9	−0.1 (3)
O2—S1—N1—C1	49.53 (18)	C6—C7—C8—C9	−1.6 (3)
O2—S1—N1—C4	−168.70 (17)	C6—C7—C8—C11	178.9 (2)
O2—S1—C5—C6	168.76 (16)	C7—C8—C9—C10	0.5 (3)
O2—S1—C5—C10	−13.4 (2)	C8—C9—C10—C5	0.3 (3)
N1—S1—C5—C6	−76.84 (19)	C10—C5—C6—C7	−0.9 (3)
N1—S1—C5—C10	100.97 (19)	C11—C8—C9—C10	−179.9 (2)
N1—C1—C2—C3	−31.6 (3)

Hydrogen-bond geometry (Å, º) top

Cg2 is the centroid of the C5–C10 ring.

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···O1ⁱ	0.95	2.46	3.406 (3)	174
C10—H10···O2	0.95	2.54	2.917 (3)	104
C11—H11C···Cg2ⁱⁱ	0.98	2.73	3.614 (3)	150

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

Acknowledgements

The authors thank Pfizer, Inc. for the donation of a Varian INOVA 400 FT NMR spectrometer. The CCD-based X-ray diffractometers at Michigan State University were upgraded and/or replaced by departmental funds.

Funding information

Funding for this research was provided by: National Science Foundation (grant No. MRI CHE-1725699); Grand Valley State University Chemistry Department's Weldon Fund.

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