Chiral Elaboration of Gold Nanoparticle Surfaces by Bis(binaphthyl) Groups

Mohammad Nuruzzaman; Thomas C. Preston; Silvia Mittler; Nathan D. Jones

doi:10.1055/s-2007-1000865

LETTER

Chiral Elaboration of Gold Nanoparticle Surfaces by Bis(binaphthyl) Groups

Mohammad Nuruzzaman^a, Thomas C. Preston^a, Silvia Mittler^b, Nathan D. Jones*^a
^a Department of Chemistry, The University of Western Ontario, London, ON, N6A 5B7, Canada
e-Mail: njones26@uwo.ca; Fax: +1(519)6613022;
^b Department of Physics and Astronomy, The University of Western Ontario, London, ON, N6A 5B7, Canada

Abstract

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Abstract

The synthesis of a family of bis(binaphthyl)-based compounds for the chiral modification of gold nanoparticle surfaces is described. In these systems, two (S)-1,1′-bi-2-naphthol groups are linked to one another by a single diethanolamine-derived bridge, the nitrogen atom of which serves as an anchor for the attachment of an alkanethiol tether of 6, 10, or 12 methylene units in length. The terminal thiol group allows the production of surface-elaborated gold nanoparticles of 2.1 ± 0.6 nm diameter by a ‘direct synthesis’ method.

Key words

chirality - binaphthol - nanoparticle - gold - surface

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References

References and Notes

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To a stirred solution of 3 (16.0 g, 37.85 mmol) in acetone (200 mL), 4 (10.0 g, 15.14 mmol) and K₂CO₃ (31.7 g, 229 mmol) were added. The mixture was heated to reflux for 24 h. After cooling to r.t., H₂O was added and the solution was extracted with EtOAc. The organic layer was dried over Na₂SO₄ and concentrated under reduced pressure. Purification by column chromatography (10-30% EtOAc-hexanes) gave the pure compound 5 (16.32 g) in 93% yield. ¹H NMR (CDCl₃): δ = 2.42-2.60 (m, 4 H), 3.20-3.45 (m, 4 H), 6.01 (s, 2 H), 6.65-7.34 (m, 40 H), 7.40-7.88 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 14.52, 21.36, 47.23, 60.68, 67.84, 82.46, 114.59, 117.24, 119.96, 126.78, 134.29, 141.68, 149.59. MS: m/z = 1181 [M + Na]⁺, 1158 [M⁺], 364, 338, 242. HRMS: m/z calcd for C₇₆H₅₈N₂O₈SNa: 1181.3864; found: 1181.3897.

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To a stirred solution of 5 (15.0 g, 12.94 mmol) in DMF (250 mL) were added K₂CO₃ (7.15 g, 51.76 mmol) and 4-methylbenzenethiol (3.21 g, 25.88 mmol). Water was added after overnight stirring at r.t. The aqueous layer was extracted several times with EtOAc, and the combined organic fractions were washed with 1 M NaOH and H₂O, and dried over Na₂SO₄. After removal of the solvent, the crude product was purified by column chromatography (40% EtOAc-hexanes) to give 6 (11.47 g) in 91% yield. ¹H NMR (CDCl₃): δ = 1.98-2.18 (m, 4 H), 3.40-3.59 (m, 4 H), 6.10 (s, 2 H), 6.80-7.38 (m, 36 H), 7.70 (dd, 4 H), 7.90 (dd, 4 H). ¹³C{¹H} NMR (CDCl₃): δ = 47.91, 68.97, 82.61, 115.20, 117.35, 120.16, 121.78, 123.77, 124.02, 125.74, 127.42, 134.31, 134.40, 141.93, 142.09, 153.46, 154.44. MS: m/z = 973 [M⁺], 521, 286. HRMS: m/z calcd for C₇₀H₅₅NO₄: 973.4131; found: 973.4105.

Compounds 7a-c were made using modifications to reported procedures. Compound 7a is a known compound. See:

<A NAME="RS04807ST-28A">28a</A> Sharma GVM. Reddy ChG. Krishna PR. J. Org. Chem. 2003, 68: 4574

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Compound 7b is likewise known. See:

<A NAME="RS04807ST-28D">28d</A> Imagawa H. Tsuchihashi T. Singh RK. Yamamoto H. Sugihara T. Nishizawa M. Org. Lett. 2003, 5: 153

<A NAME="RS04807ST-28E">28e</A> Hashimoto M. Liu Y. Fang K. Li H.-Y. Campiani G. Nakanishi K. Bioorg. Med. Chem. 1999, 7: 1181

The preparation of 7c was as follows: To a suspension of 60% NaH (1.38 g, 95.79 mmol) in THF (80 mL) and DMF (15 mL) at r.t. was added a solution of 1,12-dodecanediol (12.92 g, 63.86 mmol) in THF (50 mL). The mixture was stirred at r.t. for 30 min, and a solution of p-methoxybenzyl chloride (5.0 g, 31.93 mmol) in THF (20 mL) and TBAB (0.2 g, 0.64 mmol) were added. The mixture was stirred at 60 °C for 4 d and then cooled to r.t., and quenched with sat. NH₄Cl. The solvent was removed in vacuo, extracted with EtOAc, washed with H₂O and brine, dried over Na₂SO₄, and concentrated under reduced pressure. The crude material was purified by column chromatography (30% EtOAc-hexanes) to give the pure product 7c (5.59 g) in 54% yield. ¹H NMR (CDCl₃): δ = 1.26-1.39 (m, 16 H), 1.54-1.70 (m, 4 H), 3.42 (t, J = 6.6 Hz, 2 H), 3.63 (q, J = 6.6 Hz, 2 H), 3.79 (s, 3 H), 4.43 (s, 2 H), 6.86 (d, J = 8.8 Hz, 2 H), 7.26 (d, J = 8.8 Hz, 2 H). ¹³C{¹H} NMR (CDCl₃): δ = 25.96, 26.42, 29.65, 29.69, 29.78, 29.99, 33.03, 55.49, 63.28, 70.46, 72.72, 113.96, 129.45, 131.03, 159.30. MS: m/z = 322 [M⁺], 137, 121. HRMS: m/z calcd for C₂₀H₃₄O₃: 322.2508; found: 322.2497.

Compounds 8a-c were made using modifications to reported procedures. Compound 8a is a known compound. See ref. 28a-c. Compound 8b is likewise known. See ref. 28d,e. The preparation of 8c was as follows: To a solution of 7c (5.45 g, 16.90 mmol) in CH₂Cl₂ (100 mL) at 0 °C, imidazole (2.3 g, 33.80 mmol) and Ph₃P (8.86 g, 33.80 mmol) were added under N₂ and the mixture was stirred at the same temperature for 10-15 min. Then, I₂ (8.58 g, 33.80 mmol) was added (by portion) and the mixture was stirred at 0 °C for an additional 30 min. The resultant mixture was diluted with CH₂Cl₂, washed with 1 M HCl, H₂O and brine, dried over Na₂SO₄, and concentrated under reduced pressure to give the crude product. Purification by column chromatography (10% EtOAc-hexanes) afforded compound 8c (6.31 g) in 86% yield. ¹H NMR (CDCl₃): δ = 1.26-1.39 (m, 16 H), 1.57-1.60 (m, 2 H), 1.79-1.83 (m, 2 H), 3.18 (t, J = 7.2 Hz, 2 H), 3.43 (t, J = 6.8 Hz, 2 H), 3.80 (s, 3 H), 4.43 (s, 2 H), 6.86 (d, J = 8.8 Hz, 2 H), 7.26 (d, J = 8.8 Hz, 2 H). ¹³C{¹H} NMR (CDCl₃): δ = 7.57, 26.43, 28.76, 29.63, 29.70, 29.76, 29.79, 30.01, 30.74, 33.79, 55.51, 70.46, 72.73, 113.96, 129.43, 131.05, 159.31. MS: m/z = 432 [M⁺], 228, 121. HRMS: m/z calcd for C₂₀H₃₃IO₃: 432.1525; found: 432.1520.

The preparation of 9a is given as a typical procedure: To a solution of 6 (1.0 g, 1.03 mmol) in acetone (40 mL), K₂CO₃ (1.14 g, 8.24 mmol) was added and the mixture was brought to reflux for 30 min. After cooling to r.t., a solution of iodide 8a (896 mg, 2.57 mmol) in acetone (10 mL) was added slowly and the mixture was again heated to reflux for 3 d. After cooling to r.t., H₂O was added and the solution was extracted with EtOAc. The organic layer was dried over Na₂SO₄ and concentrated under reduced pressure. Purification by column chromatography (10-30% EtOAc-hexanes) gave the pure compound 9a (1.17 g) in 95% yield. ¹H NMR (CDCl₃): δ = 0.71-0.75 (m, 4 H), 1.03-1.07 (m, 2 H), 1.43-1.49 (m, 2 H), 1.61-1.67 (m, 2 H), 2.15 (br s, 4 H), 3.38 (t, J = 6.4 Hz, 2 H), 3.48-3.57 (m, 4 H), 3.81 (s, 3 H), 4.45 (s, 2 H), 6.08 (s, 2 H), 6.89-7.36 (m, 40 H), 7.73 (dd, J = 9.2, 8.4 Hz, 4 H), 7.94 (dd, J = 8.0, 9.2 Hz, 4 H). ¹³C{¹H} NMR (CDCl₃): δ = 26.06, 26.73, 27.42, 29.24, 29.74, 31.68, 52.37, 54.99, 55.23, 68.01, 70.20, 72.49, 82.18, 113.74, 116.97, 123.64, 125.58, 125.63, 128.03, 134.13, 153.16, 154.54, 159.08. MS: m/z = 1194 [M + H]⁺, 546, 409. HRMS: m/z calcd for C₈₄H₇₅NO₆: 1194.5678; found: 1194.5680.
Compound 9b: 79% yield. ¹H NMR (CDCl₃): δ = 0.71-0.79 (m, 4 H), 0.97-1.42 (m, 10 H), 1.65-1.78 (m, 4 H), 2.19 (br s, 4 H), 3.45-3.65 (m, 6 H), 3.80 (s, 3 H), 4.48 (s, 2 H), 6.12 (s, 2 H), 6.90-7.38 (m, 40 H), 7.73 (dd, J = 8.8, 7.6 Hz, 4 H), 7.94 (t, J = 8.8 Hz, 4 H). ¹³C{¹H} NMR (CDCl₃): δ = 26.58, 27.26, 27.85, 29.89, 29.92, 30.14, 52.77, 55.55, 68.35, 70.56, 72.83, 82.54, 114.05, 115.14, 117.33, 119.94, 125.92, 128.07, 134.45, 142.05, 142.21, 153.50, 154.88, 159.39. MS: m/z = 1250 [M⁺]. HRMS: m/z calcd for C₈₈H₈₃NO₆: 1250.6299; found: 1250.6293.
Compound 9c: 81% yield. ¹H NMR (CDCl₃): δ = 0.71-0.79 (m, 4 H), 1.19-1.45 (m, 14 H), 1.65-1.78 (m, 4 H), 2.19 (br s, 4 H), 3.45-3.65 (m, 6 H), 3.80 (s, 3 H), 4.48 (s, 2 H), 6.12 (s, 2 H), 6.90-7.38 (m, 40 H), 7.73 (dd, J = 8.8, 7.6 Hz, 4 H), 7.94 (t, J = 8.8 Hz, 4 H). ¹³C{¹H} NMR (CDCl₃): δ = 26.56, 27.28, 27.86, 29.99, 52.75, 55.44, 68.33, 70.54, 72.81, 82.53, 114.04, 115.11, 117.32, 119.92, 121.97, 123.64, 125.00-131.10 (m), 134.45, 142.20, 153.49, 154.87, 159.38. MS: m/z = 1278 [M⁺], 549, 509. HRMS: m/z calcd for C₉₀H₈₇NO₆: 1278.6645; found: 1278.6631.

The preparation of 10a is given as a typical procedure: To a solution of 9a (1.0 g, 0.84 mmol) in EtOAc-MeOH (1:1, 40 mL), 10% Pd/C (300 mg) was carefully added. After stirring at r.t. for 4 d under H₂ atmosphere, the catalyst was filtered off and the filtrate was reduced to dryness in vacuo. The crude material was purified by column chromatography (60% EtOAc-hexanes) to afford the product 10a (587 mg) in 81% yield. ¹H NMR (CDCl₃): δ = 0.78-1.15 (m, 6 H), 1.32-1.41 (m, 2 H), 1.88-2.15 (m, 2 H), 2.19-2.30 (m, 2 H), 2.31-2.42 (m, 2 H), 3.30 (t, J = 8.8 Hz, 2 H), 3.58-3.78 (m, 7 H), 4.45 (s, 2 H), 6.87-7.38 (m, 22 H), 7.80-7.95 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 26.16, 26.75, 27.42, 29.74, 32.57, 51.56, 54.42, 62.96, 66.42, 114.99, 116.97, 123.64, 125.58, 125.63, 128.03, 134.13, 153.16, 154.54. MS: m/z = 862 [M⁺], 550, 242. HRMS: m/z calcd for C₅₈H₅₅NO₆: 862.4081; found: 862.4073.
Compound 10b: 63% yield. ¹H NMR (CDCl₃): δ = 0.82-1.42 (m, 14 H), 1.59-1.72 (m, 2 H), 1.96-2.18 (m, 2 H), 2.25-2.35 (m, 2 H), 2.44-2.58 (m, 2 H), 3.45 (t, J = 8.8 Hz, 2 H), 3.60-3.78 (m, 7 H), 4.35 (s, 2 H), 6.87-7.38 (m, 22 H), 7.80-7.94 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 26.19, 26.27, 29.41, 29.44, 29.51, 29.76, 51.55, 54.23, 55.23, 66.37, 54.23, 55.23, 66.37, 70.21, 72.48, 113.72, 114.64, 116.87, 116.92, 118.94, 123.20, 124.02, 125.05, 125.16, 127.94, 133.91, 151.61, 154.43, 159.06. MS: m/z = 918 [M⁺], 749, 509, 219. HRMS: m/z calcd for C₆₂H₆₃NO₆: 918.4734; found: 918.4724.
Compound 10c: 50% yield. ¹H NMR (CDCl₃): δ = 0.81-1.38 (m, 18 H), 1.48-1.62 (m, 2 H), 1.93-2.42 (m, 2 H), 2.23-2.35 (m, 2 H), 2.46-2.57 (m, 2 H), 3.43 (t, J = 8.8 Hz, 2 H), 3.68-3.84 (m, 7 H), 4.45 (s, 2 H), 6.86-7.37 (m, 22 H), 7.80-7.94 (m, 8 H). ¹³C {¹H} NMR: δ = 26.46, 27.40, 27.86, 29.82, 51.75, 55.49, 70.47, 72.73, 113.96, 114.88, 117.17, 119.22, 123.48, 129.65, 130.62, 134.22, 151.86, 154.81. MS: m/z = 946 [M⁺]. HRMS: m/z calcd for C₆₄H₆₇NO₆: 946.5022; found: 946.5020.

The preparation of 11a is given as a typical procedure: To an ice-cold mixture of 10a (400 mg, 0.46 mmol) in CH₂Cl₂/H₂O (10:1, 11 mL) was added 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 211 mg, 0.92 mmol) in one portion. The mixture was stirred at 0 °C for 1.5 h, and diluted with sat. NaHCO₃. The organic layer was removed, and the aqueous layer was extracted with CH₂Cl₂. The combined organic fractions were dried over Na₂SO₄ and concentrated. Purification by column chromatography (70% EtOAc-hexanes) gave 11a (264 mg) in 77% yield. ¹H NMR (CDCl₃): δ = 0.78-1.15 (m, 6 H), 1.32-1.41 (m, 2 H), 1.88-2.15 (m, 2 H), 2.19-2.30 (m, 2 H), 2.31-2.42 (m, 2 H), 3.42 (t, J = 6.8 Hz, 2 H), 3.61-3.78 (m, 4 H), 4.45 (s, 2 H), 6.87-7.38 (m, 18 H), 7.78-7.95 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 25.49, 26.17, 26.75, 29.93, 32.56, 51.55, 54.42, 62.96, 66.42, 114.98, 119.04, 123.46, 124.37, 125.22, 125.40, 126.53, 127.29, 128.27, 129.65, 130.62, 134.20, 151.87, 154.58. MS: m/z = 842 [M⁺], 639, 430, 242. HRMS: m/z calcd for C₅₀H₄₇NO₅: 742.3532; found: 742.3535.
Compound 11b: 60% yield. ¹H NMR (CDCl₃): δ = 0.82-1.52 (m, 14 H), 1.72-1.74 (m, 2 H), 1.76-2.02 (m, 2 H), 2.22-2.45 (m, 4 H), 3.43 (t, J = 6.8 Hz, 2 H), 3.50-3.78 (m, 4 H), 6.87-7.42 (m, 18 H), 7.58-7.94 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 25.86, 26.14, 27.11, 29.46, 32.89, 51.53, 54.73, 63.17, 66.21, 114.93, 116.89, 117.36, 119.15, 123.47, 124.37, 125.22, 125.41, 126.54, 127.26, 128.20, 129.66, 134.19, 151.93, 154.54. MS: m/z = 798 [M⁺], 549. HRMS: m/z calcd for C₅₄H₅₅NO₅: 798.4181; found: 798.4185.
Compound 11c: 45% yield. ¹H NMR (CDCl₃): δ = 0.77-1.31 (m, 18 H), 1.45-1.49 (m, 2 H), 1.86-2.20 (m, 2 H), 2.23-2.35 (m, 2 H), 2.46-2.57 (m, 2 H), 3.54 (t, J = 6.8 Hz, 2 H), 3.64-3.73 (m, 4 H), 6.87-7.29 (m, 18 H), 7.73-7.86 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 25.96, 26.50, 27.39, 29.67, 32.96, 51.77, 54.54, 63.22, 66.57, 114.93, 117.13, 117.37, 118.24, 119.26, 123.45, 124.29, 125.31, 125.46, 125.62, 127.45, 128.27, 128.54, 129.62, 129.76, 134.23, 151.96, 154.68. MS: m/z = 826 [M⁺], 549. HRMS: m/z calcd for C₅₆H₅₉NO₅: 826.4431; found: 826.4441.

<A NAME="RS04807ST-33A">33a</A> Ramachandran PV. Prabhudas B. Chandra JS. Reddy MVR. J. Org. Chem. 2004, 69: 6294

<A NAME="RS04807ST-33B">33b</A> Delgado M. Martin JD. J. Org. Chem. 1999, 64: 4798

The preparation of 2a is given as a typical procedure: To a solution of 11a (200 mg, 0.27 mmol) in CH₂Cl₂ (10 mL), imidazole (55 mg, 0.81 mmol) and Ph₃P (212 mg, 0.87 mmol) were added and the mixture was stirred at r.t. for about 10-15 min. The mixture was cooled to 0 °C and I₂ (137 mg, 0.54 mmol) was added. After 1 h, 1 M HCl was added. The mixture was diluted with CH₂Cl₂, washed with H₂O and brine, dried over Na₂SO₄, and concentrated under reduced pressure to give the crude iodide. To a stirred solution of the iodide in THF (5 mL), a mixture of TBAF (92 mg, 0.35 mmol) and hexamethyldisilathiane (85 µL, 0.41 mmol) in THF (5 mL) were added and the mixture was stirred at 0 °C for 30 min before being allowed to warm to r.t. After 12 h, 1 M HCl was added. The mixture was diluted with CH₂Cl₂, washed with sat. NH₄Cl solution, H₂O and brine, dried over Na₂SO₄, and concentrated under reduced pressure. Purification by column chromatography (70% EtOAc-hexanes) gave pure 2a in 45% yield over both steps. ¹H NMR (CDCl₃): δ = 0.65-1.15 (m, 6 H), 1.32-1.58 (m, 2 H), 1.88-1.98 (m, 2 H), 2.19-2.42 (m, 4 H), 3.42 (t, J = 6.8 Hz, 2 H), 3.61-3.82 (m, 4 H), 6.87-7.38 (m, 18 H), 7.78-7.95 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 24.82, 25.95, 26.67, 27.25, 32.48, 51.45, 54.30, 62.50, 65.35, 113.96, 118.85, 123.45, 124.30, 125.18, 125.36, 126.48, 127.10, 128.25, 129.59, 130.45, 151.78, 154.48. MS: m/z = 760 [M⁺]. HRMS: m/z calcd for C₅₀H₄₇NO₄S: 760.3477; found: 760.3461.
Compound 2b: 40% yield. ¹H NMR (CDCl₃): δ = 0.65-1.18 (m, 14 H), 1.62-1.78 (m, 2 H), 1.80-2.02 (m, 2 H), 2.18-2.45 (m, 4 H), 3.15 (t, J = 6.8 Hz, 2 H), 3.50-3.78 (m, 4 H), 6.87-7.42 (m, 18 H), 7.58-7.94 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 24.95, 26.10, 26.98, 29.30, 31.90, 51.49, 54.60, 63.28, 65.15, 114.85, 116.64, 116.38, 119.05, 123.35, 124.26, 125.18, 125.37, 126.50, 127.21, 128.18, 129.50, 130.67, 134.50, 151.85, 154.49. MS: m/z = 816 [M⁺]. HRMS: m/z calcd for C₅₄H₅₅NO₄S: 816.3744; found: 816.3750.
Compound 2c: 30% yield. ¹H NMR (CDCl₃): δ = 0.68-1.28 (m, 18 H), 1.38-1.52 (m, 2 H), 1.90-2.18 (m, 2 H), 2.20-2.31 (m, 2 H), 2.38-2.50 (m, 2 H), 3.20 (t, J = 6.8 Hz, 2 H), 3.58-3.67 (m, 4 H), 6.88-7.31 (m, 18 H), 7.73-7.86 (m, 8 H). ¹³C{¹H} NMR (CDCl₃): δ = 25.20, 26.25, 27.14, 29.30, 31.89, 32.56, 51.62, 54.59, 63.30, 66.18, 114.89, 116.70, 116.89, 119.36, 123.38, 124.20, 125.19, 125.37, 126.50, 127.20, 128.28, 129.54, 130.87, 134.26, 151.89, 154.60. MS: m/z = 841 [M⁺]. HRMS: m/z calcd for C₅₅H₅₉NO₄S: 841.4165; found: 841.4170.

<A NAME="RS04807ST-35">35</A> See, for example: Fitzmaurice D. Rao SN. Preece JA. Stoddart JF. Wenger S. Zaccheroni N. Angew. Chem. Int. Ed. 1999, 38: 1147

To a stirred solution of tetraoctylammonium bromide (36 mg, 0.66 mmol) in CHCl₃ (3 mL), HAuCl₄ (5 mg, 0.015 mmol) in H₂O (2 mL) was added. The mixture was stirred vigorously for approximately 10 min, and separation between the orange-red organic phase and colorless aqueous phase resulted. The organic layer was collected and compound 2b (6 mg, 0.007 mmol) in CHCl₃ (2 mL) was added to the organic phase. After an additional 10 min of stirring, a solution of NaBH₄ (5.60 mg, 0.147 mmol) in H₂O (2 mL) was slowly added. The orange-red color turned to black-brown, and the reaction mixture was vigorously stirred for 3 d. The organic layer was collected, and reduced to 2 mL. Ethanol (100 mL) was then added, and the mixture was kept at 0 °C for 12 h. The precipitated nanocrystals were isolated by centrifugation and washed with EtOH and acetone.

<A NAME="RS04807ST-37">37</A> Hostetler MJ. Wingate JE. Zhong C.-J. Harris JE. Vachet RW. Clark MR. Londono JD. Green SJ. Stokes JJ. Wignall GD. Glish GL. Porter MD. Evans ND. Murray RW. Langmuir 1998, 14: 17

<A NAME="RS04807ST-38">38</A> For simple alkyl- and arylthiol-stabilized particles see ref. 10a (biphasic synthesis, 1-3 nm) and 10b (single-phase synthesis, mean 5 nm), respectively. For a more complex thiol ligand, see ref. 35 (ca. 4 nm). Amine-stabilized particles made using this route are typically much larger (25-70 nm). See: Leff DV. Brandt L. Heath JR. Langmuir 1996, 12: 4723 ; for citrate-stabilized particles (>10 nm), see ref. 9a