SUPPORTING INFORMATION

Transcription

1 Electronic Supplementary Material (ESI) for CrystEngComm. This journal is The Royal Society of Chemistry 2014 SUPPORTING INFORMATION A Stimuli-Responsive Double-Stranded Digold(I) Helicate Csaba Jobbágy, Miklós Molnár, Péter Baranyai, Andrea Hamza, Gábor Pálinkás, and Andrea Deák*, Hungarian Academy of Sciences, MTA TTK SZKI Lendület Supramolecular Chemistry Laboratory MTA TTK MFI and MTA TTK SZKI Laboratory of Theoretical Chemistry, H-1117 Budapest, Magyar Tudósok körútja 2, Hungary

2 S-2 Physical Measurements SEM images were taken on a ZEISS EVO 40XVP Scanning Electron Microscope (accelerating voltage: 20 kv, W-filament). TEM images were taken using a FEI MORGAGNI 268D Transmission Electron Microscope (accelerating voltage: 100 kv, W-filament). One drop of the solution or suspension was placed on a copper grid coated with carbon, which was then dried in vacuum. Steady state and time-resolved luminescence measurements were carried out on an Edinburgh Instrument FLSP920 spectrofluorimeter. Spectral corrections were applied using excitation and emission correction functions of the instrument. Merck spectroscopy-grade solvents were used for AIE measurements. The solid-state room temperature emission studies were conducted on finely ground powder samples placed on a Quartz Suprasil plate in a front face sample holder. Photoluminescence spectra of II G were recorded on crystals placed with a small amount of mother liquor in a 5 mm quartz tube. Longpass filters were used to exclude the scattered excitation light. The excitation light source was a μf900h xenon flashlamp (pulse duration: 2 μs at FWHM) for the luminescent lifetime measurements. Powder diffractograms were produced with Cu-K radiation on a vertical high-angle Philips PW 1050 powder diffractometer.

3 S-3 X-ray Crystallography and Data Collection Crystal data, data collection and refinement details for I B, I B(RT), II G and III Y are listed in Table S1. Table S1 Crystal data and structure refinement parameters for I B (low temperature data), I B(RT) (room temperature data), II G and III Y, respectively. Complex I B I B(RT) II G III Y Formula C 78 H 64 Au 2 O 2 P 4,2(NO 3 ), 2.64(CH 2 Cl 2 ) Formula weight Crystal size [mm] C 78 H 64 Au 2 O 2 P 4,2(NO 3 ), 2.26(CH 2 Cl 2 ) C 78 H 64 Au 2 O 2 P 4,2(NO 3 ), 4.69(CH 2 Cl 2 ) C 78 H 64 Au 2 O 2 P 4,2(NO 3 ), 1.9(CH 2 Cl 2 ),0.59(H 2 O) Colour colourless colourless colourless colourless Crystal system Space group monoclinic monoclinic monoclinic monoclinic C 2/c C 2/c C 2/c P 2 1 /c Temp. (K) a [Å] (7) (5) (5) (1) b [Å] (3) (5) (4) (3) c [Å] (5) (5) (4) (2) α [ ] [ ] (2) (5) (1) (1) γ [ ] V [Å 3 ] 7383(3) 7625(3) 8363(3) (12) Z d calc [Mg/m 3 ] [mm 1 ] No. of obsd. reflns. I > 2 (I) No. of parameters GOF R1 (obsd. data) wr2 (all data)

4 S-4 General Procedures Materials. All chemicals and solvents used for the syntheses were of reagent grade. The solvents for synthesis were used without further purification. All manipulations were performed in air. 1 was prepared according to a published procedure. 1 Preparation of 1: A mixture of Au(SMe 2 )Cl (150 mg, mmol), xantphos (294.3 mg, mmol) and AgNO 3 (86.5 mg, mmol) in 15 ml dichloromethane was stirred for 6 hours, shielded from light. The AgCl precipitate was filtered through Celite, and the solvent was removed under vacuum. The white solid was collected and washed with diethyl ether. Yield: 391 mg (91.7%). This material was used to obtain different crystalline and amorphous samples of 1. Production of blue luminescent I B microcrystalline powder: A mg (0.255 mmol) of 1 was dissolved in 15 ml of dichloromethane. The as-resulting clear solution was then filtered through Celite. To this filtrate 30 ml of diethyl ether was rapidly added under vigorous stirring. The asresulting I B microcrystalline powder was filtered off and washed with cold diethyl ether. Elemental analysis calcd (%) for CH 2 Cl 2 : C 52.43, H 3.73, N 1.53; found: C 52.11, H 3.85, N Production of amorphous red IV R(desolv. IIG) form obtained upon desolvation of bluish green II G emitting crystals: Desolvation of bluish green II G luminescent crystals at room temperature produced the amorphous red IV R(desolv. IIG) form. Elemental analysis calcd (%) for CH 2 Cl 2 : C 53.53, H 3.77, N 1.58; found: C 53.91, H 3.62, N The photographs taken under of hand held UV lamp (365 nm) illumination of microcrystalline blue I B and amorphous red IV R(desolv IIG) obtained upon desolvation of bluish green II G emitting crystals are shown in Fig. S1. Fig. S1 Photographs taken under hand held UV lamp (365 nm) illumination showing the: A) microcrystalline blue emitting I B(microcryst.) and B) amorphous red emitting IV R(desolv. IIG) form obtained upon desolvation of bluish green II G emitting crystals.

5 S-5 The I B crystals retain their solvent of crystallization after standing in air for several months. Its desolvated I B(desolv.) can be obtained by heating the I B crystals under reduced pressure at 90 C for 20 minutes. This blue emitting I B(desolv.) form retains its original emission colour (Fig. S2), and its PXRD pattern (Fig. S3) shows sharp lines suggesting retention of crystallinity upon solvent removal. Fig. S2 Emission and excitation spectra (λ ex = 365 nm) of crystalline I B, microcrystalline I B(microcryst.) and its desolvated I B(desolv.) form. Fig. S3 PXRD patterns of a) crystalline I B, b) its desolvated I B(desolv.) and c) microcrystalline I B(microcryst.) forms compared to the d) calculated pattern simulated from the single crystal structure of I B.

6 S-6 Fig. S4 Emission spectra (λ ex = 365 nm) of II G crystals showing their emission colour change upon thermal stimuli from bluish green through green and yellow to red emitting amorphous IV R(desolv. IIG) form obtained as a result of desolvation. Fig. S5 PXRD patterns of amorphous a) IV R and b) IV R(desolv. IIG) forms.

7 S-7 Fig. S6 Emission and excitation spectra (λ ex = 365 nm) of yellow emitting III Y and desolvated III Y(desolv.) form. Fig. S7 PXRD patterns of a) crystalline III Y and b) its desolvated III Y(desolv.) form compared to the c) calculated pattern simulated from the single crystal structure of III Y.

8 S-8 2. Single Crystal X-ray Diffraction Selected bond lengths, angles and torsion angles are listed in Table S2. The ORTEP view with thermal ellipsoids at the 50% probability level of the Au 2 L 2 unit of I B, I B(RT), II G and III Y forms are shown in Fig. S8 S11. Overlaid low-temperature I B (blue coloured) and room-temperature I B(RT) (red coloured) molecular structures of dinuclear double stranded [Au 2 L 2 ] 2+ helicate are shown in Fig. S12. Molecular structures of the Au 2 L 2 unit (I B, I B(RT), II G and III Y ) with labelled centroids are shown in Fig. S13, S15, S17 and S19. The analysis of short π π ring, C H X (X = π, O, Cl), N O π, C Cl π and O H O interactions has been performed by using the PLATON, 2 and the results are listed in Tables S3 S18.

9 Fig. S8 ORTEP view of the Au 2 L 2 unit in complex I B with thermal ellipsoids at the 50% probability level. S-9

10 Fig. S9 ORTEP view of the Au 2 L 2 unit in complex I B(RT) with thermal ellipsoids at the 50% probability level. S-10

11 Fig. S10 ORTEP view of the Au 2 L 2 unit in complex II G with thermal ellipsoids at the 50% probability level. S-11

12 Fig. S11 ORTEP view of the Au 2 L 2 unit in complex III Y with thermal ellipsoids at the 50% probability level. S-12

13 S-13 Table S2 Selected bond lengths (Å), angles ( ) and torsion angles ( ) for complexes I B, I B(RT), II G and III Y, respectively. I B I B(RT) II G III Y Au(1) Au(1) i 2.838(1) 2.837(1) 2.863(1) Au(1) Au(1 ) 2.841(1) Au(1) P(1) 2.342(2) 2.344(2) 2.336(2) Au(1) P(2) i 2.334(2) 2.336(2) 2.332(2) Au(1) P(1) 2.316(1) Au(1 ) P(1 ) 2.319(1) Au(1) P(2 ) 2.318(1) Au(1 ) P(2) 2.314(1) P(1) Au(1) P(2) i 166.0(1) 165.1(1) 160.8(1) P(1) Au(1) P(2 ) 159.2(1) P(1 ) Au(1 ) P(2) 159.7(1) P(1) Au(1) Au(1) i P(1) i 103.2(1) 103.6(1) 113.5(1) P(1) Au(1) Au(1') P(1') 110.3(1) P(1) Au(1) Au(1) i P(2) 83.8(1) 83.6(1) 78.1(1) P(1) Au(1) Au(1') P(2) 78.5(1) P(2) Au(1) i Au(1) P(2) i 89.1(1) 89.2(1) 90.3(1) P(2) Au(1) Au(1') P(2') 91.2(1) 78.1(1) P(2') Au(1) Au(1') P(1') 80.0(1) Operators for generating equivalent atoms: i = b = 2 X, Y, ½ Z for I B and i = a = 2 X, Y, 3/2 Z for II G.

14 Fig. S12 Overlaid low-temperature I B (blue coloured) and room-temperature I B(RT) (red coloured) molecular structures of dinuclear double stranded [Au 2 L 2 ] 2+ helicate S-14

15 S-15 Fig. S13 View of the Au 2 L 2 unit with labelled centroids of complex I B. X 1, X 2 and X 3 are the centroids of the C(1) C(2) C(3) C(4) C(5) C(13), O(1) C(12) C(7) C(6) C(5) C(13) and C(7) C(8) C(9) C(10) C(11) C(12) xanthene ring. A, B, C, and D are the centroids of the C(1A) C(2A) C(3A) C(4A) C(5A) C(6A), C(1B) C(2B) C(3B) C(4B) C(5B) C(6B), C(1C) C(2C) C(3C) C(4C) C(5C) C(6C) and C(1D) C(2D) C(3D) C(4D) C(5D) C(6D) phenyl rings. Symmetry code: i = [2755] = 2 X, Y, 1/2 Z. Colours: carbon, grey; hydrogen, dark-brown; oxygen, red; phosphorus, orange; gold, yellow. Table S3 Analysis of short intramolecular π π ring interactions in blue emitting I B crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage A [ 1] -> B [ ] 4.943(4) (3) (3) 3.244(3) A [ 1] -> C [ ] 3.981(4) (3) (3) (3) B [ 1] -> X 1 [ ] 5.118(4) (3) (3) (3) C [ 1] -> A [ ] 3.980(4) (3) (3) (3) C [ 1] -> D [ ] 5.011(4) (3) (3) 3.396(3) D [ 1] -> X 3 [ ] 5.047(4) (3) (3) (3) X 3 [ 1] -> C [ ] 5.088(4) (3) (3) (3) X 1 [ 1] -> D [ ] 5.422(4) (3) (3) 5.033(3) B [ 1] -> A [ ] 5.275(4) (3) (3) 4.101(3) D [ 1] -> X 1 [ ] 5.422(4) (3) (3) 4.294(3) X 3 [ 1] -> D [ ] 4.817(4) (3) (3) 4.677(3) X 3 [ 1] -> X 3 [ ] 5.524(4) (3) 3.958(3) [ 1555] = X,Y,Z [ 2755] = 2-X,Y,1/2-Z = i symmetry equivalent part of the molecule

16 S-16 Fig. S14 A view along a) the a axis and b) b axis depicting the arrangement of dinuclear double stranded [Au 2 L 2 ] 2+ helicates in the crystal structure of I B. Intermolecular π π interactions are shown as dashed lines (centroid labelling and symmetry codes are given in Table S4). In I B crystal, the [Au 2 L 2 ] 2+ helicates are packed into head-to-tail fashion to form columnar stacks (Fig. S14) based on π π interactions between the xanthene chromophore and phenyl groups (X 3 A vii 5.082(4) Å, A C iv 5.839(5) Å; centroid labelling and symmetry codes are given in Table S4). These columnar stacks are also held together by π π interactions (X 1 X ii (4) Å, X 1 B ii 5.319(4) Å, X 1 D iii 4.843(4) Å, C X iii (4) Å, D D vi 3.700(4) Å; centroid labelling and symmetry codes are given in Table S4).

17 S-17 Table S4 Analysis of short intermolecular π π ring interactions in blue emitting I B crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage X 1 [ 1] -> X 1 [ ] 4.870(4) (3) (3) X 1 [ 1] -> B [ ] 5.319(4) (3) (3) (3) X 1 [ 1] -> D [ ] 4.843(4) (3) (3) 4.524(3) A [ 1] -> C [ ] 5.839(5) (3) (3) 5.243(3) C [ 1] -> X 1 [ ] 5.950(4) (3) (3) 5.917(3) D [ 1] -> D [ ] 3.700(4) (3) 3.361(3) X 3 [ 1] -> A [ ] 5.082(4) (3) (3) (3) Centroids are: X 1 is the centroid of the C(1) C(13) ring of the xanthene unit X 2 is the centroid of the O(1) C(13) ring of the xanthene unit X 3 is the centroid of the C(7) C(12) ring of the xanthene unit A is the centroid of the C(1A) C(6A) ring of the phenyl group B is the centroid of the C(1B) C(6B) ring of the phenyl group C is the centroid of the C(1C) C(6C) ring of the phenyl group D is the centroid of the C(1D) C(6D) ring of the phenyl group Symmetry codes: ii = [ 7665] = 3/2-X,3/2-Y,-Z iii = [ 4564] = X,1-Y,-1/2+Z iv = [ 6655] = 3/2-X,1/2+Y,1/2-Z v = [ 4565] = X,1-Y,1/2+Z vi = [ 3766] = 2-X,1-Y,1-Z vii = [ 6645] = 3/2-X,-1/2+Y,1/2-Z Where: Cg(I) = Plane number I (= ring number in () above) Alpha = Dihedral Angle between Planes I and J (Deg) Beta = Angle Cg(I)-->Cg(J) or Cg(I)-->Me vector and normal to plane I (Deg) Gamma = Angle Cg(I)-->Cg(J) vector and normal to plane J (Deg) Cg-Cg = Distance between ring Centroids (Ang.) CgI_Perp = Perpendicular distance of Cg(I) on ring J (Ang.) CgJ_Perp = Perpendicular distance of Cg(J) on ring I (Ang.) Slippage = Distance between Cg(I) and Perpendicular Projection of Cg(J) on Ring I (Ang). P,Q,R,S = J-Plane Parameters for Carth. Coord. (Xo, Yo, Zo)

18 S-18 Table S5 Analysis of C H π interactions in blue emitting I B crystal Intramolecular X--H(I) Res(I) Cg(J) [ ARU(J)] H..Cg Transformed J-Plane P, Q, R, S H-Perp Gamma X-H..Cg X..Cg X-H,Pi C(2D) -H(2D) [ 1] -> C [ ] (7) 20 C(6D) -H(6D) [ 1] -> X 3 [ ] (7) 62 [ 1555] = X,Y,Z [ 2755] = 2-X,Y,1/2-Z = i symmetry equivalent part of the molecule Intermolecular X--H(I) Res(I) Cg(J) [ ARU(J)] H..Cg Transformed J-Plane P, Q, R, S H-Perp Gamma X-H..Cg X..Cg X-H,Pi C(3D) -H(3D) [ 1] -> X 1 [ ] (9) 54 C(4A) -H(4A) [ 1] -> X 3 [ ] (9) 61 Min or Max [ 4565] = X,1-Y,1/2+Z [ 6655] = 3/2-X,1/2+Y,1/2-Z Centroids are: 6-Membered Ring (X 1 ) C(1) C(2) C(3) C(4) C(5) C(13) 6-Membered Ring (X 3 ) C(7) C(8) C(9) C(10) C(11) C(12) 6-Membered Ring (C) C(1C) C(2C) C(3C) C(4C) C(5C) C(6C) where: Cg(J) = Center of gravity of ring J (Plane number above) H-Perp = Perpendicular distance of H to ring plane J Gamma = Angle between Cg-H vector and ring J normal X-H..Cg = X-H-Cg angle (degrees) X..Cg = Distance of X to Cg (Angstrom) X-H, Pi = Angle of the X-H bond with the Pi-plane (i.e.' Perpendicular = 90 degrees, Parallel = 0 degrees)

19 S-19 Table S6 Analysis of C H O and C H Cl interactions in blue emitting I B crystal Nr Typ Res Donor --- H...Acceptor [ ARU ] D - H H...A D...A D - H...A 2 1 C(3C) --H(3C)..Cl(3) [ ] (10) C(3B) --H(3B)..O(2) [ ] (9) C(4B) --H(4B)..O(2) [ ] (9) C(5B) --H(5B)..O(4) [ ] (11) C(8) --H(8)..O(3) [ ] (9) C(10) --H(10)..Cl(2) [ ] (9) C(16) --H(16A)..O(2) [ ] (19) 129 [ 6655.] = [ 4_655] = 3/2-x,1/2+y,1/2-z [ 6645.] = [ 4_645] = 3/2-x,-1/2+y,1/2-z [ 8564.] = [ 8_565] = 1/2+x,3/2-y,-1/2+z [ 2655.] = [ 2_655] = 1-x,y,1/2-z

20 S-20 Fig. S15 View of the Au 2 L 2 unit with labelled centroids of complex I B(RT). X 1, X 2 and X 3 are the centroids of the C(1) C(2) C(3) C(4) C(5) C(13), O(1) C(12) C(7) C(6) C(5) C(13) and C(7) C(8) C(9) C(10) C(11) C(12) xanthene ring. A, B, C, and D are the centroids of the C(1A) C(2A) C(3A) C(4A) C(5A) C(6A), C(1B) C(2B) C(3B) C(4B) C(5B) C(6B), C(1C) C(2C) C(3C) C(4C) C(5C) C(6C) and C(1D) C(2D) C(3D) C(4D) C(5D) C(6D) phenyl rings. Symmetry code: i = [2755] = 2 X, Y, 1/2 Z. Colours: carbon, grey; hydrogen, dark-brown; oxygen, red; phosphorus, orange; gold, yellow. Table S7 Analysis of short intramolecular π π ring interactions in blue emitting I B(RT) crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage X 1 [ 1] -> A [ ] 5.208(4) (4) (3) (3) X 1 [ 1] -> D [ ] 5.374(5) (4) (3) 4.992(3) A [ 1] -> B [ ] 4.963(5) (4) (3) 3.230(3) A [ 1] -> C [ ] 4.085(5) (4) (3) (4) B [ 1] -> X 1 [ ] 5.098(5) (4) (3) (3) B [ 1] -> A [ ] 5.274(5) (4) (3) 4.158(3) C [ 1] -> A [ ] 4.084(5) (4) (4) (3) C [ 1] -> D [ ] 4.950(5) (4) (4) 3.446(3) D [ 1] -> X 1 [ ] 5.374(5) (4) (3) 4.214(3) D [ 1] -> X 3 [ ] 5.035(4) (4) (3) (3) X 3 [ 1] -> C [ ] 5.050(5) (4) (3) (4) X 3 [ 1] -> D [ ] 4.899(5) (4) (3) 4.755(3) X 3 [ 1] -> X 3 [ ] 5.591(5) (3) 4.089(3) [ 1555] = X,Y,Z [ 2755] = 2-X,Y,1/2-Z = i symmetry equivalent part of the molecule

21 S-21 Fig. S16 A view along a) the a axis and b) b axis depicting the arrangement of dinuclear double stranded [Au 2 L 2 ] 2+ helicates in the crystal structure of I B(RT). Intermolecular π π interactions are shown as dashed lines (centroid labelling and symmetry codes are given in Table S8). In I B(RT) crystal, the [Au 2 L 2 ] 2+ helicates are packed into head-to-tail fashion to form columnar stacks (Fig. S16) based on π π interactions between the xanthene chromophore and phenyl groups (X 3 A vii 5.229(5) Å, A C iv 5.804(5) Å; centroid labelling and symmetry codes are given in Table S8). These columnar stacks are also held together by π π interactions (X 1 X ii (4) Å, X 1 B ii 5.398(5) Å, X 1 D iii 5.074(5) Å, C X iii (5) Å, D D vi 3.887(5) Å; centroid labelling and symmetry codes are given in Table S8).

22 S-22 Table S8 Analysis of short intermolecular π π ring interactions in blue emitting I B(RT) crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage X 1 [ 1] -> X 1 [ ] 5.107(4) (3) (3) X 1 [ 1] -> B [ ] 5.398(5) (4) (3) (4) X 1 [ 1] -> D [ ] 5.074(5) (4) (3) 4.695(3) A [ 1] -> C [ ] 5.804(5) (4) (3) 5.091(4) C [ 1] -> X 1 [ ] 5.899(5) (4) (4) 5.802(3) D [ 1] -> D [ ] 3.887(5) (3) 3.462(3) X 3 [ 1] -> A [ ] 5.229(5) (4) (3) (3) Centroids are: X 1 is the centroid of the C(1) C(13) ring of the xanthene unit X 2 is the centroid of the O(1) C(13) ring of the xanthene unit X 3 is the centroid of the C(7) C(12) ring of the xanthene unit A is the centroid of the C(1A) C(6A) ring of the phenyl group B is the centroid of the C(1B) C(6B) ring of the phenyl group C is the centroid of the C(1C) C(6C) ring of the phenyl group D is the centroid of the C(1D) C(6D) ring of the phenyl group Symmetry codes: ii = [ 7665] = 3/2-X,3/2-Y,-Z iii = [ 4564] = X,1-Y,-1/2+Z iv = [ 6655] = 3/2-X,1/2+Y,1/2-Z v = [ 4565] = X,1-Y,1/2+Z vi = [ 3766] = 2-X,1-Y,1-Z vii = [ 6645] = 3/2-X,-1/2+Y,1/2-Z Where: Cg(I) = Plane number I (= ring number in () above) Alpha = Dihedral Angle between Planes I and J (Deg) Beta = Angle Cg(I)-->Cg(J) or Cg(I)-->Me vector and normal to plane I (Deg) Gamma = Angle Cg(I)-->Cg(J) vector and normal to plane J (Deg) Cg-Cg = Distance between ring Centroids (Ang.) CgI_Perp = Perpendicular distance of Cg(I) on ring J (Ang.) CgJ_Perp = Perpendicular distance of Cg(J) on ring I (Ang.) Slippage = Distance between Cg(I) and Perpendicular Projection of Cg(J) on Ring I (Ang). P,Q,R,S = J-Plane Parameters for Carth. Coord. (Xo, Yo, Zo)

23 S-23 Table S9 Analysis of C H π interactions in blue emitting I B(RT) crystal Intramolecular X--H(I) Res(I) Cg(J) [ ARU(J)] H..Cg Transformed J-Plane P, Q, R, S H-Perp Gamma X-H..Cg X..Cg X-H,Pi C(2D) -H(2D) [ 1] -> C [ ] (8) 22 C(6D) -H(6D) [ 1] -> X 3 [ ] (7) 62 [ 1555] = X,Y,Z [ 2755] = 2-X,Y,1/2-Z = i symmetry equivalent part of the molecule Intermolecular X--H(I) Res(I) Cg(J) [ ARU(J)] H..Cg Transformed J-Plane P, Q, R, S H-Perp Gamma X-H..Cg X..Cg X-H,Pi C(3D) -H(3D) [ 1] -> X 1 [ ] (9) 56 Min or Max [ 4565] = X,1-Y,1/2+Z Centroids are: 6-Membered Ring (X 1 ) C(1) C(2) C(3) C(4) C(5) C(13) 6-Membered Ring (X 3 ) C(7) C(8) C(9) C(10) C(11) C(12) 6-Membered Ring (C) C(1C) C(2C) C(3C) C(4C) C(5C) C(6C) where: Cg(J) = Center of gravity of ring J (Plane number above) H-Perp = Perpendicular distance of H to ring plane J Gamma = Angle between Cg-H vector and ring J normal X-H..Cg = X-H-Cg angle (degrees) X..Cg = Distance of X to Cg (Angstrom) X-H, Pi = Angle of the X-H bond with the Pi-plane (i.e.' Perpendicular = 90 degrees, Parallel = 0 degrees) Table S10 Analysis of C H O and C H Cl interactions in blue emitting I B(RT) crystal Nr Typ Res Donor --- H...Acceptor [ ARU ] D - H H...A D...A D - H...A 1 1 C(4B) --H(4B)..O(2) [ ] (15) C(5B) --H(5B)..O(2) [ ] (15) C(5C) --H(5C)..O(4) [ ] (16) C(8) --H(8)..O(3) [ ] (18) 137 [ 6655.] = [ 4_655] =3/2-x,1/2+y,1/2-z [ 8564.] = [ 8_565] =1/2+x,3/2-y,-1/2+z [ 7666.] = [ 7_666] =3/2-x,3/2-y,1-z [ 6645.] = [ 4_645] =3/2-x,-1/2+y,1/2-z

24 S-24 Fig. S17 View of the Au 2 L 2 unit with labelled centroids in complex II G. X 1, X 2 and X 3 are the centroids of the C(1) C(2) C(3) C(4) C(5) C(13), O(1) C(12) C(7) C(6) C(5) C(13) and C(7) C(8) C(9) C(10) C(11) C(12) xanthene ring. A, B, C, and D are the centroids of the C(1A) C(2A) C(3A) C(4A) C(5A) C(6A), C(1B) C(2B) C(3B) C(4B) C(5B) C(6B), C(1C) C(2C) C(3C) C(4C) C(5C) C(6C) and C(1D) C(2D) C(3D) C(4D) C(5D) C(6D) phenyl rings. Symmetry code: i = 2 X, Y, 3/2 Z. Colours: carbon, grey; hydrogen, dark-brown; oxygen, red; phosphorus, orange; gold, yellow. Table S11 Analysis of short intramolecular π π ring interactions in green emitting II G crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage A [ 1] -> B [ ] 4.972(6) (4) (4) (4) A [ 1] -> C [ ] 3.754(6) (5) (4) 3.317(4) B [ 1] -> X 1 [ ] 5.133(5) (4) (4) (4) C [ 1] -> A [ ] 3.755(6) (5) (4) (4) C [ 1] -> D [ ] 5.006(5) (5) (4) 3.168(4) D [ 1] -> X 3 [ ] 5.030(6) (5) (4) 3.209(4) X 3 [ 1] -> C [ ] 5.075(6) (5) (4) 3.226(4) X 1 [ 1] -> D [ ] 4.988(5) (4) (4) 4.867(4) B [ 1] -> A [ ] 5.789(5) (4) (4) 3.086(4) X 3 [ 1] -> D [ ] 5.126(6) (5) (4) (4) X 3 [ 1] -> X 3 [ ] 5.084(5) (4) (4) [ 1555] = X,Y,Z [ 2756] = 2-X,Y,3/2-Z= i symmetry equivalent part of the molecule

25 S-25 Fig. S18 A view along a) the c axis and b) b axis depicting the arrangement of dinuclear double stranded [Au 2 L 2 ] 2+ helicates in the crystal structure of II G. Intermolecular π π interactions are shown as dashed lines (centroid labelling and symmetry codes are given in Table S12). In bluish green emitting II G crystals, the dinuclear [Au 2 L 2 ] 2+ helicates are arranged into dimers through slipped π π interactions between the xanthene chromophores (X 3 X 3 v 5.362(6) Å, slippage of 1.64 Å) and xanthene and phenyl rings (C X 3 v 5.799(5) Å and A A iii 4.410(5) Å), showing a brick-wall packing pattern (Fig. S18). Here each dimer overlaps via additional π π interactions with two halves of dimers in the row above and below (X 1 X 1 ii 4.931(6) Å, X 1 B ii 5.990(6) Å, B D iv 5.468(5) Å, D X 1 vi 4.978(5) Å, centroid labelling and symmetry codes are given in Table S12).

26 S-26 Table S12 Analysis of short intermolecular π π ring interactions in blue emitting II G crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage X 1 [ 1] -> X 1 [ ] 4.931(6) (4) 3.288(4) X 1 [ 1] -> B [ ] 5.990(6) (4) (4) 3.201(4) A [ 1] -> A [ ] 4.410(5) (4) (4) B [ 1] -> D [ ] 5.468(5) (4) (4) (4) C [ 1] -> X 3 [ ] 5.799(5) (5) (4) 3.383(4) D [ 1] -> X 1 [ ] 4.978(5) (4) (4) (4) X 3 [ 1] -> X 3 [ ] 5.362(6) (4) 5.103(4) Centroids are: X 1 is the centroid of the C(1) C(13) ring of the xanthene unit X 2 is the centroid of the O(1) C(13) ring of the xanthene unit X 3 is the centroid of the C(7) C(12) ring of the xanthene unit A is the centroid of the C(1A) C(6A) ring of the phenyl group B is the centroid of the C(1B) C(6B) ring of the phenyl group C is the centroid of the C(1C) C(6C) ring of the phenyl group D is the centroid of the C(1D) C(6D) ring of the phenyl group Symmetry codes: ii = [ 7656] = 3/2-X,1/2-Y,1-Z iii = [ 3756] = 2-X,-Y,1-Z iv = [ 8454] = -1/2+X,1/2-Y,-1/2+Z v = [ 3766] = 2-X,1-Y,1-Z vi = [ 8555] = 1/2+X,1/2-Y,1/2+Z Where: Cg(I) = Plane number I (= ring number in () above) Alpha = Dihedral Angle between Planes I and J (Deg) Beta = Angle Cg(I)-->Cg(J) or Cg(I)-->Me vector and normal to plane I (Deg) Gamma = Angle Cg(I)-->Cg(J) vector and normal to plane J (Deg) Cg-Cg = Distance between ring Centroids (Ang.) CgI_Perp = Perpendicular distance of Cg(I) on ring J (Ang.) CgJ_Perp = Perpendicular distance of Cg(J) on ring I (Ang.) Slippage = Distance between Cg(I) and Perpendicular Projection of Cg(J) on Ring I (Ang). P,Q,R,S = J-Plane Parameters for Carth. Coord. (Xo, Yo, Zo)

27 S-27 Table S13 Analysis of C H O and C H Cl interactions in green emitting II G crystal Intramolecular Nr Typ Res Donor --- H...Acceptor [ ARU ] D - H H...A D...A D - H...A 3 1 C(6B) --H(6B)..O(3) [ ] (13) C(16) --H(16A)..O(2) [ ] (19) C(16) --H(16B)..Cl(4) [ ] (15) C(5C) --H(5C)..O(2) [ ] (14) C(6C) --H(6C)..O(3) [ ] (12) 134 [ 2756.] = [ 2_756] = 2-x,y,3/2-z Intermolecular Nr Typ Res Donor --- H...Acceptor [ ARU ] D - H H...A D...A D - H...A 1 1 C(4) --H(4)..O(3) [ ] (11) 154 [ 7656.] = [ 7_656] =3/2-x,1/2-y,1-z

28 Fig. S19 View of the Au 2 L 2 unit with labelled centroids in complex III Y. X 1, X 2, X 3 and X 1, X 2, X 3 are the centroids of the C(1) C(2) C(3) C(4) C(5) C(13), O(1) C(12) C(7) C(6) C(5) C(13) and C(7) C(8) C(9) C(10) C(11) C(12) and C(1 ) C(2 ) C(3 ) C(4 ) C(5 ) C(13 ), O(1 ) C(12 ) C(7 ) C(6 ) C(5 ) C(13 ) and C(7 ) C(8 ) C(9 ) C(10 ) C(11 ) C(12 ) xanthene rings. A, B, C, D and A, B, C, D are the centroids of the C(1A) C(2A) C(3A) C(4A) C(5A) C(6A), C(1B) C(2B) C(3B) C(4B) C(5B) C(6B), C(1C) C(2C) C(3C) C(4C) C(5C) C(6C) and C(1D) C(2D) C(3D) C(4D) C(5D) C(6D) and C(1A ) C(2A ) C(3A ) C(4A ) C(5A ) C(6A ), C(1B ) C(2B ) C(3B ) C(4B ) C(5B ) C(6B ), C(1C ) C(2C ) C(3C ) C(4C ) C(5C ) C(6Cv) and C(1D ) C(2D ) C(3D ) C(4D ) C(5D ) C(6D ) phenyl rings. Colours: carbon, grey; hydrogen, dark-brown; oxygen, red; phosphorus, orange; gold, yellow. S-28

29 S-29 Table S14 Analysis of short intramolecular π π ring interactions in yellow emitting III Y crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage X 1 [ 1] -> D [ ] 5.005(3) (3) (2) 4.946(3) X 1 [ 1] -> D [ ] 5.006(3) (3) (2) (3) A [ 1] -> B [ ] 5.001(3) (3) (2) (3) A [ 1] -> C [ ] 4.018(4) (3) (2) 3.648(3) A [ 1] -> B [ ] 4.968(3) (3) (3) 3.385(2) A [ 1] -> C [ ] 4.097(4) (3) (3) (3) B [ 1] -> X 1 [ ] 5.033(3) (3) (2) 3.176(2) B [ 1] -> A [ ] 5.820(3) (3) (2) (2) C [ 1] -> A [ ] 4.097(4) (3) (3) 3.234(3) C [ 1] -> D [ ] 5.099(4) (3) (3) (3) D [ 1] -> X 3 [ ] 5.006(4) (3) (3) (3) D [ 1] -> X 3 [ ] 5.173(4) (3) (3) (2) X 3 [ 1] -> C [ ] 4.980(4) (3) (3) (2) X 3 [ 1] -> X 3 [ ] 5.149(3) (3) (2) 3.813(2) X 3 [ 1] -> D [ ] 5.361(3) (3) (3) 5.111(2) X 3 [ 1] -> D [ ] 5.173(4) (3) (2) (3) X 3 [ 1] -> X 3 [ ] 5.149(3) (3) (2) (2) X 3 [ 1] -> C [ ] 5.141(4) (3) (2) 3.048(2) B [ 1] -> X 1 [ ] 4.993(4) (3) (3) (2) B [ 1] -> A [ ] 5.728(4) (3) (3) 3.626(3) C [ 1] -> A [ ] 4.018(4) (3) (3) (2) C [ 1] -> D [ ] 4.967(3) (3) (3) 3.470(2) D [ 1] -> X 3 [ ] 5.082(3) (3) (2) (2) [ 1555] = X, Y, Z

30 S-30 Fig. S20 A view along a) the c axis and b) a axis depicting the arrangement of dinuclear double stranded [Au 2 L 2 ] 2+ helicates in the crystal structure of III Y. Intermolecular π π interactions are shown as dashed lines (centroid labelling and symmetry codes are given in Table S15). In yellow emitting III Y crystal, the twisted-core Au 2 L 2 units form helical chains (Fig. S20) based on π π interactions between the xanthene chromophores and phenyl groups (X 1 C i 5.604(3) Å, X 1 D i 5.750(3) Å, X 1 A ii 4.786(3) Å, X 1 C ii 5.612(3) Å, B D i 5.479(4) Å, C X v (4) Å, D X v (4) Å, B C v 5.256(4) Å, C D i 5.667(3) Å, D D i 3.899(4) Å). These helices are also held together by π π interactions (A X iii (4) Å, B B iv 5.825(3) Å, B X iii (3) Å, D A vi 5.639(4) Å, X 3 B vi 5.531(4) Å, D B vi 5.246(4) Å, centroid labelling and symmetry codes are given in Table S15).

31 S-31 Table S15 Analysis of short intermolecular π π ring interactions in yellow emitting III Y crystal Cg(I) Res(I) Cg(J) [ ARU(J)] Cg-Cg Transformed J-Plane P, Q, R, S Alpha Beta Gamma CgI_Perp CgJ_Perp Slippage X 1 [ 1] -> C [ ] 5.604(3) (3) (2) 3.016(3) X 1 [ 1] -> D [ ] 5.750(3) (3) (2) 4.781(3) X 1 [ 1] -> A [ ] 4.786(3) (3) (2) 4.593(2) X 1 [ 1] -> C [ ] 5.612(3) (3) (2) 4.316(3) A [ 1] -> X 3 [ ] 5.410(4) (3) (2) 5.142(3) B [ 1] -> B [ ] 5.825(3) (2) 2.997(2) B [ 1] -> X 3 [ ] 4.853(3) (3) (2) (2) B [ 1] -> D [ ] 5.479(4) (3) (2) 4.092(2) C [ 1] -> X 1 [ ] 5.778(4) (3) (3) (2) D [ 1] -> A [ ] 5.639(4) (3) (3) (3) D [ 1] -> X3 [ ] 5.784(4) (3) (3) 5.031(3) X3 [ 1] -> B [ ] 5.531(4) (3) (3) 3.896(2) B [ 1] -> C [ ] 5.256(4) (3) (3) (3) C [ 1] -> D [ ] 5.667(3) (3) (3) 4.489(2) D [ 1] -> B [ ] 5.246(4) (3) (2) (3) D [ 1] -> D [ ] 3.899(4) (3) 3.661(3) Centroids are: X 1 is the centroid of the C(1) C(13) ring of the xanthene unit X 2 is the centroid of the O(1) C(13) ring of the xanthene unit X 3 is the centroid of the C(7) C(12) ring of the xanthene unit A is the centroid of the C(1A) C(6A) ring of the phenyl group B is the centroid of the C(1B) C(6B) ring of the phenyl group C is the centroid of the C(1C) C(6C) ring of the phenyl group D is the centroid of the C(1D) C(6D) ring of the phenyl group X 1 is the centroid of the C(1 ) C(13 ) ring of the xanthene unit X 2 is the centroid of the O(1 ) C(13 ) ring of the xanthene unit X 3 is the centroid of the C(7 ) C(12 ) ring of the xanthene unit A is the centroid of the C(1A ) C(6A ) ring of the phenyl group B is the centroid of the C(1B ) C(6B ) ring of the phenyl group C is the centroid of the C(1C ) C(6C ) ring of the phenyl group D is the centroid of the C(1D ) C(6D ) ring of the phenyl group Symmetry codes: i = [ 3577] = -X,2-Y,2-Z ii = [ 3576] = -X,2-Y,1-Z iii = [ 1655] = 1+X,Y,Z iv = [ 3677] = 1-X,2-Y,2-Z v = [ 4564] = X,3/2-Y,-1/2+Z vi = [ 1455] = -1+X,Y,Z vii = [ 4565] = X,3/2-Y,1/2+Z

32 S-32 Where: Cg(I) = Plane number I (= ring number in () above) ; Alpha = Dihedral Angle between Planes I and J (Deg) Beta = Angle Cg(I)-->Cg(J) or Cg(I)-->Me vector and normal to plane I (Deg) Gamma = Angle Cg(I)-->Cg(J) vector and normal to plane J (Deg) Cg-Cg = Distance between ring Centroids (Ang.); CgI_Perp = Perpendicular distance of Cg(I) on ring J (Ang.) CgJ_Perp = Perpendicular distance of Cg(J) on ring I (Ang.) Slippage = Distance between Cg(I) and Perpendicular Projection of Cg(J) on Ring I (Ang). P,Q,R,S = J-Plane Parameters for Carth. Coord. (Xo, Yo, Zo)

33 S-33 Table S16 Analysis of C H π interactions in yellow emitting III Y crystal Intermolecular X--H(I) Res(I) Cg(J) [ ARU(J)] H..Cg Transformed J-Plane P, Q, R, S H-Perp Gamma X-H..Cg X..Cg X-H,Pi C5A' -H5A' [ 1] -> X 1 [ ] (6) 56 C9' -H9' [ 1] -> B [ ] (6) 51 Min or Max [ 3576] = -X,2-Y,1-Z [ 1455] = -1+X,Y,Z Centroids are: 6-Membered Ring (B) C(1B) C(2B) C(3B) C(4B) C(5B) C(6B) 6-Membered Ring (X 1 ) C(1) C(2) C(3) C(4) C(5) C(13) where: Cg(J) = Center of gravity of ring J (Plane number above) H-Perp = Perpendicular distance of H to ring plane J Gamma = Angle between Cg-H vector and ring J normal X-H..Cg = X-H-Cg angle (degrees) X..Cg = Distance of X to Cg (Angstrom) X-H, Pi = Angle of the X-H bond with the Pi-plane (i.e.' Perpendicular = 90 degrees, Parallel = 0 degrees) Table S17 Analysis N O π interactions in yellow emitting III Y crystal Y--X(I) Res(I) Cg(J) [ ARU(J)] X..Cg Transformed J-Plane P, Q, R, S X-Perp Gamma Y-X..Cg Y..Cg Y-X,Pi N1 -O3 [ 2] -> X 3 [ ] 3.528(8) (6) 4.775(10) N2 -O5 [ 3] -> X 1 [ ] 3.418(7) (4) 3.701(6) 5.02 Min or Max [ 2446] = -1-X,-1/2+Y,3/2-Z [ 4464] = -1+X,3/2-Y,-1/2+Z

34 S-34 Table S18 Analysis of O H O, C H O and C H Cl interactions in yellow emitting III Y crystal Nr Typ Res Donor --- H...Acceptor [ ARU ] D - H H...A D...A D - H...A 1 O8 --H8A..O7 [ ] 0.84(4) 2.25(10) 2.816(10) 124(10) 2 1 C3A' --H3A'..O3 [ ] (11) C2B --H2B..O6 [ ] (8) C4A' --H4A'..O2 [ ] (8) C4' --H4'..O2 [ ] (8) C4C --H4C..O8 [ ] (12) C5D --H5D..O7 [ ] (8) C3B' --H3B'..O4 [ ] (15) C5B' --H5B'..O5 [ ] (9) C5C' --H5C'..O4 [ ] (11) C14' --H14E..O3 [ ] (11) C16 --H16A..O7 [ ] (9) C16 --H16B..O2 [ ] (8) C17 --H17A..O2 [ ] (9) C17 --H17B..O6 [ ] (9) C3' --H3'..Cl1 [ ] (6) 156 [ 4665.] = [ 4_676] =1+x,3/2-y,1/2+z [ 2556.] = [ 2_556] =-x,1/2+y,3/2-z [ 4564.] = [ 4_575] =x,3/2-y,-1/2+z [ 2456.] = [ 2_456] =-1-x,1/2+y,3/2-z [ 4664.] = [ 4_675] =1+x,3/2-y,-1/2+z [ 1655.] = [ 1_655] =1+x,y,z

35 S-35 Computational Approach In the present study density functional theory (DFT) calculations were performed by using the Gaussian 09 3 program package at the B3LYP/6-31G* level of theory. Single point calculations were effectuated for structures I B, II G, III Y fixed in their X-ray geometry, obtained in low temperature experiments, as well as for structure I B(RT) as obtained in high temperature experiments. The Wood- Boring quasi-relativistic Stuttgart/Dresden type (SDD) pseudopotential and basis set have been used for the Au(I) atoms which is well suited to account for relativistic effects important in case of aurophilic interactions. The Grimme s D3 empirical dispersion correction 4 to the density functional had been used to correctly describe the noncovalent interaction between the aromatic rings. In order to investigate the Au Au bond we carried out Mayer s bond order analysis 5 as implemented in the Gaussian 09 suite. In Table S19 we present the calculated data. The results show that the change of the bond order indices is not significant in case of structures I B, II G. In case of I B(RT) the bond order is almost invariable compared to its low-temperature analogue, which correlates well with the very small change in the Au Au distance due to the thermal motion. Structure III Y is somewhat different in the sense, that the bond order analysis shows a slightly strengthen of the aurophilic interaction, however this is at the margin of the error of calculations. In conclusion, the confinement of the helicate units in the different environment of the three crystal structures induces very slight modulation of the inner Au Au interaction. Table S19 Electronic energies (in Hartree) of structures I B, II G, III Y, I B(RT), Au Au distance (in Ångstrom) and Mayer s bond order indices structure E Au Au Bond order I B -4797, II G -4797, III Y -4797, I B(RT) -4796,

36 S-36 Aggregation induced emission Preparation of microstructures of 1: Stock solutions of 1 in dichloromethane (filtered by membrane filter with 0.45 μm pore size) with a concentration of M were prepared. Aliquots (5 μl) of the stock solutions were transferred to 10 ml flasks and were diluted with appropriate amount of dichloromethane. Diethyl ether was added dropwise into a dichloromethane solution of 1 under vigorous stirring to furnish M solutions with defined fractions of diethyl ether (f Et2O = vol %). PL measurements of the resultant aggregate suspensions were performed after one hour of stirring. The morphological properties of different forms of 1 obtained by varying the composition of the solvent mixtures were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TEM and SEM images (Fig. S21) indicate that different well-formed microstructures were formed in the mixtures with 60% 90% diethyl ether content, while spherical particles were present at 99.5% diethyl ether fraction. This simple method can thus be used for the fabrication of gold-based microstructures.

37 a) b) c) d) e) f) g) h) i) j) Fig. S21 SEM (a, c, e, g, i) and TEM (b, d, f, h, j) images of aggregates of 1 formed in dichloromethane/diethyl ether mixtures with 60% (a, b), 70% (c, d), 80% (e, f), 90% (g, h) and 99.5% (i, j) diethyl ether content. S-37

38 S-38 Stimuli-responsive luminescence When the blue emitting I B crystals were ground in a mortar the luminescence colour of the as-formed ground sample IV R(ground IB) changed to red (Fig. S22). Fig. S22 Photographs taken under hand-held UV lamp irradiation (365 nm) showing the switching between blue and red luminescence upon grinding and fuming: a) finely ground powder of I B, b) powder after grinding the right-half with a pestle, c) entirely ground red emitting powder of IV R(ground IB), d) formation of I B(IVR ground IB) and reversion to the blue luminescence after fuming with dichloromethane onto the centre of the orange luminescent IV R(ground IB) powder. This crystalline-to-amorphous transformation induced by grinding results in a remarkable change of the luminescence colour from intense blue to red. The molecules in the I B crystalline state have significantly longer lifetime than in IV R(ground IB) amorphous state. However, the original blue luminescence restored when the red emitting IV R(ground IB) was exposed to dichloromethane vapour (vapochromic luminescence), indicating a reversible luminescence colour change. This newly formed I B(IVR ground IB) solid shows an emission spectrum identical to that of original I B, and it has quite similar lifetimes to that of microcrystalline I B(microcryst.) (τ 1 = 280 μs (40 %), τ 2 = 1000 μs (60%)).

39 S-39 Acknowledgement We are grateful to Dr Csaba Németh for his assistance in recording the FTIR spectra. We thank Dr László Szabó and Eszter Drotár for SEM and TEM measurements and useful discussions. References 1 A. Deák, T. Megyes, G. Tárkányi, P. Király, L. Biczók, G. Pálinkás, P. J. Stang, J. Am. Chem. Soc., 2006, 128, A. L. Spek, PLATON, A Multipurpose Crystallographic Tool, Utrecht University, Utrecht, The Netherlands, Gaussian 09, Revision D.01, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian, Inc., Wallingford CT, S. Grimme, J. Antony, S. Ehrlich and H. Krieg, J. Chem. Phys., 2010, 132, I. Mayer, Chem. Phys. Lett., 1983, 97, 270.