Materials. All reactions were carried out under a dry argon atmosphere using Schlenk techniques and vacuum-line systems. The solvents were dried, distilled, and degassed prior to use. Spectroscopic grade reagents for spectroscopic measurements were purchased from commercial sources. 3,6-Di-tert-butyl-1,8-diethynyl-9H-carbazole (H2L) was prepared by similar procedure described in literature.41
Synthesis of (HNEt3)2[Au6Cu4L4(HL)4] (1). To a freshly prepared CH2Cl2 (10 mL) solution of Au(tht)2ClO4 (0.06 mmol, 28.4 mg) were added Cu(CH3CN)4ClO4 (0.04 mmol, 13.1 mg) and H3decz (0.08 mmol, 26.2 mg), followed by the dropwise addition of NEt3 (20 uL) under vigorous stirring. The stirring was kept for three minutes to blend thoroughly all reagents. The reaction flask was then sealed and put aside with exclusion of light for one week to give the product as yellow plate-like crystals. Yield: 78%. Anal. Calcd for Au6Cu4C204H220N10: C, 57.68; H, 5.22; N, 3.30. Found: C, 57.54; H, 5.44; N, 3.26 (after desolvation). HRMS m/z (%): 2021.5012 (100) [M-(HNEt3)2]2- (Calcd 2021.5083). 1H NMR (400 MHz, DMSO-d6, δ): 10.35 (s, 4H), 9.87 (s, 4H), 8.37 (s, 4H), 8.29 (s, 4H), 7.73 (s, 4H), 7.61 (s, 4H), 7.38 (s, 4H), 7.20 (s, 4H), 6.94 (s, 4H), 6.31 (s, 4H), 4.66 (s, 4H), 3.36–3.31 (m, 12H), 1.48 (s, 36H), 1.37 (s, 36H), 1.24–1.22 (m, 18H), 0.66 (s, 36H), 0.14 (s, 36H). IR (KBr, cm-1): 3362m (N‒H), 3310m (CºC-H), 2102w (CºC).
Synthesis of (HNEt3)2[Au10Cu4L8(dppb)2] (2). To a freshly prepared CH2Cl2 (10 mL) solution of Au(tht)2ClO4 (0.1 mmol, 47.3 mg) were added Cu(CH3CN)4ClO4 (0.04 mmol, 13.1 mg), dppb (0.02 mmol, 8.5 mg) and H3decz (0.08 mmol, 26.2 mg), followed by the addition of NEt3 (20 uL) under vigorous stirring. The reaction mixture was continuously stirred overnight in the absent of light. Upon removal of the solvent by rotatory evaporation, the yellow solid was dissolved in 3 mL dimethylacetamide (DMAc) to give a clear yellow solution. Layering Et2O onto the solution through slow diffusion gave yellow block crystals within one week. Yield: 63%.
Alternatively, complex 2 was prepared by mixing a CH2Cl2 solution of complex 1 with 4 equiv. Au(tht)2ClO4 and 2 equiv. dppb in the presence of NEt3. The solution was evaporated through rotary evaporator to dryness to give yellow solid. Yellow crystals were obtained by layering Et2O onto a DMAc solution in one week. Yield: 58%. Anal. Calcd for C260H272Au10Cu4N10P4: C, 53.07; H, 4.66; N, 2.38. Found: C, 53.26; H, 4.79; N, 2.36 (after desolvation). HRMS m/z (%): 2840.0980 (100) [M-(HNEt3)2]2- (Calcd 2840.0936). 1H NMR (400 MHz, CD2Cl2, δ): 11.06 (s, 4H), 10.21 (s, 4H), 8.02 (s, 4H), 7.67 (s, 4H), 7.44 (s, 4H), 7.34 (dd, J = 12.1, 7.8 Hz, 8H), 7.21 (s, 4H), 7.17–6.86 (m, 32H), 6.70 (t, J = 7.2 Hz, 8H), 6.59 (s, 4H), 6.05 (s, 4H), 4.10–3.94 (m, 5H), 3.03–2.87 (m, 18H), 2.40–2.23 (m, 5H), 1.49 (s, 36H), 1.34 (s, 36H), 1.01–0.91 (m, 18H), 0.67 (s, 36H), 0.52 (s, 36H). 31P NMR (162 MHz, CD2Cl2, δ): 34.46 (s, 4P). IR (KBr, cm-1): 3360m (N‒H), 2105w (CºC).
Synthesis of (HNEt3)4[Au6Cu2L6] (3). To a freshly prepared CH2Cl2 (10 mL) solution of Au(tht)2ClO4 (0.06 mmol, 28.4 mg) were added Cu(CH3CN)4ClO4 (0.02 mmol, 6.5 mg) and H3decz (0.08 mmol, 26.2 mg), followed by the dropwise addition of NEt3 (20 uL). The reaction mixture was continuously stirred overnight in the absent of light. The solvent was then removed through rotatory evaporation to give a yellow solid. The crude product was washed by Et2O for three times and then redissolved in CH2Cl2 (3 mL). To the resulting yellowish solution was slowly added n-hexane to form a layer between two solvents. Yellow flat bar-like crystals were obtained within one week. Yield: 45%. Anal. Calcd for Au6Cu2C168H202N10: C, 54.98; H, 5.55; N, 3.82. Found: C, 54.91; H, 5.69; N, 3.77 (after desolvation). HRMS m/z (%): 3568.1442 (57) [M-(HNEt3)3]- (Calcd 3568.1458); 1733.0136 (100) [M-(HNEt3)2]2- (Calcd 1733.0084); 1120.9637 (86) [M-(HNEt3)]3- (Calcd 1120.9623). 1H NMR (400 MHz, CD2Cl2, δ): 10.34 (s, 6H), 7.81 (d, J = 1.4 Hz, 6H), 7.65 (d, J = 1.4 Hz, 6H), 7.54 (d, J = 1.6 Hz, 6H), 6.46 (d, J = 1.6 Hz, 6H), 3.21 (q, J = 7.1 Hz, 24H), 1.42 (s, 54H), 1.27 (t, J = 7.3 Hz, 36H), 0.69 (s, 54H). IR (KBr, cm-1): 3359m (N–H), 2097w (CºC).
Synthesis of (HNEt3)2[Au8Cu6L8] (4). To a freshly prepared CH2Cl2 (10 mL) solution of Au(tht)2ClO4 (0.08 mmol, 37.8 mg) were added Cu(CH3CN)4ClO4 (0.06 mmol, 19.6 mg) and H3decz (0.1 mmol, 32.7 mg), followed by the dropwise addition of NEt3 (20 uL) under vigorous stirring. The stirring was kept to proceed overnight in the absent of light. A large amount of yellow precipitate appeared, which was identified as Au6Cu4 complex 1 in 52% yield. After taken by filtration, the clear solution was evaporated to dryness, which was then redissolved in CH2Cl2 (3 mL). Slow diffusion of n-hexane into the solution gave red block crystals in one week. Yeild: 10%. Anal. Calcd for C204H216Au8Cu6N10: C, 51.42; H, 4.57; N, 2.94. Found: C, 51.30; H, 4.63; N, 2.82 (after desolvation). HRMS m/z (%): 2279.8914 (100) [M-(HNEt3)2]2- (Calcd 2279.8884). 1H NMR (400 MHz, CD2Cl2, δ): 10.74 (s, 2H), 9.99–9.93 (m, 4H), 9.58 (s, 2H), 8.57 (s, 4H), 8.09 (s, 2H), 8.05 (s, 2H), 7.89 (s, 2H), 7.85 (s, 2H), 7.55 (s, 4H), 7.31 (s, 2H), 7.26 (s, 2H), 7.09 (s, 4H), 6.65 (s, 4H), 5.83 (s, 2H), 5.78 (s, 2H), 3.40–3.30 (m, 12H), 1.60 (s, 72H), 1.47 (s, 36H), 1.43–1.41 (m, 18H), 0.12 (s, 36H). IR (KBr, cm-1): 3411m (N–H), 2104w (CºC).
Data availability
The data that support the findings of this study are available within the article and its Supplementary Information files. Other relevant data are available from the corresponding author upon reasonable request. The X-ray crystallographic coordinates for structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 2088667-2088670 for complexes 1-4. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.