Supporting Information for

Transcription

1 Supporting Information for Odd-Even Effects in Chiral Phase Transition at the Liquid/Solid Interface Hai Cao, a Kazukuni Tahara, bc Shintaro Itano, b Yoshito Tobe b* and Steven De Feyter a* a Division of Molecular Imaging and Photonics, Department of Chemistry, KU Leuven University of Leuven, Celestijnenlaan 200F, B3001, Leuven, Belgium. steven.defeyter@kuleuven.be b Division of Frontier Materials Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka , Japan. tobe@chem.es.osaka-u.ac.jp c Department of Applied Chemistry, School of Science and Technology, Meiji University, Higashimita, Tama-ku, Kawasaki, , Japan. Contents: Part 1. Experimental details 1.1. Synthesis of the target compounds DBA-OCn 1.2. Solution preparation 1.3. Hot deposition protocol 1.4. STM measurements 1.5. Surface coverage analysis Part 2. Supplementary results Figure S1-S3, Table S1. Supplementary STM images and information for DBA-OC12 Figure S4. DBA porous networks at the octanoic acid (OA)/HOPG interface. Figure S5. The impact of solubility on monolayer structure formation at high concentrations. Figure S6. The impact of solvent on hot deposition. Table S2. A summary of the occurrence and surface coverage of different phases for each DBA. Figure S7-14. STM images and detail information for phase transition of DBA-OC11 (S7), DBA-OC13 (S8 and S10), DBA-OC14 (S9 and S10), DBA-OC15 (S11), DBA-OC16 (S12), DBA-OC17 (S13 and S14) and DBA-OC20 (S15). Figure S16. In-situ STM measurement at 80 o C. Figure S17. Long Standing heating experiment devised to validate the stability of monolayer formed upon hot deposition protocol. Figure S18. Illustration of the gain in packing density for a racemic lattice of DBA-OC13. Figure S19. Illustration of the variation in intermolecular distance of a mismatched interdigitation of DBA-OC14. Figure S20. Mixing of DBA-OC15 and DBA-OC16. S1

2 Figure S21. Mixing of DBA-OC14 and DBA-OC15. S2

3 Part 1. Experimental Section 1.1. Synthesis of the target compounds DBA-OCn: The synthesis of DBAs has been reported previously Solution preparation: 1,2,4-trichlorobenzene (TCB, Sigma-Aldrich, 99%, used as received ), tetradecane (Sigma-Aldrich, 99%, used as received), 1-octanol (Sigma-Aldrich, 99%, used as received ), 1-phenyloctane (Sigma-Aldrich, 98%, used as received) and 1-octanoic acid (Sigma-Aldrich, 99%, used as received) were selected as solvent to dissolve DBA compounds. Various concentrations, ranging from M to M, were tested Hot deposition protocol: Firstly HOPG was heated to and held at 80 C. Then a droplet of DBA solution (about 15 μl) was applied to HOPG substrate held at 80 C for 3 min. The samples were left to cool down in the ambient for few minutes after which STM data were recorded at room temperature. STM imaging was performed at room temperature for practical reasons, as the vapor of octanoic acid may cause severe damage to the STM scanner. However, one in-situ experiment at 80 C clearly shows structures identical to those observed after cooling down (Figure S15). 80 o C was chosen for formation of uniform and regular networks, as demonstrated previously for DBA-OC13. 4 The solvent loss caused by heating is very small, around 1% STM measurements: All STM experiments were performed at room temperature (20 23 o C) using a PicoSPM (Molecular imaging, now Agilent) machine operating in constant current mode with the tip immersed in the supernatant liquid. STM tips were prepared by mechanical cutting from Pt/Ir wire (80%/20%, diameter 0.2 mm). Prior to imaging, a drop of the solution was applied onto a freshly cleaved surface of highly oriented pyrolytic graphite (HOPG, grade ZYB, Advanced Ceramics Inc., Cleveland, USA). For analysis purposes, recording of a monolayer image on HOPG was followed by consecutive imaging the graphite substrate underneath. This was done under the same experimental conditions but by lowering the substrate bias (typically V bias = 1 mv) and increasing the tunnelling current (typical I set = 800 pa). From the atomically resolved STM image of HOPG one can easily obtain the graphite symmetry axes. The images were corrected for drift via Scanning Probe Image Processor (SPIP) software (Image Metrology ApS), using the graphite lattice, allowing a more accurate unit cell determination. For a given polymorph, several high resolution STM images and corresponding underlying graphite lattices were recorded. From the corrected graphite images three main S3

4 symmetry axes and also three reference axes (normal to main symmetry axes) can be determined. The images are low-pass filtered. The typical imaging parameters for all the DBA derivatives are tunneling current (I set ) = pa and sample bias (V bias ) = mv. A STM session normally takes several hours to obtain enough images, and no significant time effect has been observed within a session. Following are two examples for the calibration of STM images Scheme S1: Calibration of STM images. S4

5 Calibration of underlying graphite lattice, using the parameters of graphite lattice, is used to correct the adlayer structure Surface coverage analysis. The percentage distribution of different phases on the surface was determined as an average based on at least two experimental sessions. Within each session, both large scale images (typically with size of 300 nm 300 nm or 200 nm 200 nm) and close-up images were obtained by moving the sample plate (after every six images) by a few millimeters. The surface coverage of each phase is calculated by SPIP software. Details for analysis, including number of images, total area and so on, are provided in Table S2. S5

6 Part 2. Supplementary results Figure S1: Large-scale STM images of DBA-OC12 upon hot deposition. Representative STM images showing large domains of different phases and the coexistence of all four phases on surface. S6

7 Figure S2: DBA porous networks at the octanoic acid (OA)/HOPG interface. Porous structures of DBAs in octanoic acid are available only at very low concentrations. It should be noted that in the case of DBA-OC13, linear network can be occasionally observed at the OA/HOPG interface even at the concentration of 1 μm. The porous networks obtained in different solvents exhibit identical lattice parameters and azimuthal orientations, and we did not find any evidence of solvent molecule co-adsorption. Both sample preparation and STM measurements were performed under ambient conditions. S7

8 Figure S3: The impact of solubility on monolayer structure formation at high concentrations. 1) TCB and 1-phenyloctane (1-PO) are good solvents for DBAs, and small domains of regular DBA linear structures can be identified together with porous networks; 2) The solubility of DBAs in octanoic acid is lower than TCB and 1- PO. Though small patches of linear structures can be observed, the monolayer structure at the OA/HOPG interface as a whole is disordered; 3) tetradecane and 1-octanol are poor solvents for DBAs, and randomly adsorbed DBAs cover the surface. Both sample preparation and STM measurements were performed under ambient conditions. S8

9 Figure S4: The impact of solvent on hot deposition. 1) Hot deposition of DBA-OC13 solution in TCB at 2 mm results in the formation of a uniform porous network; 2) In contrast, hot deposition of DBA-OC12 solution in octanoic acid at 0.5 mm leads to the emergence of exclusively high density polymorphs. S9

10 Figure S5: Supplementary STM images for phase III of DBA-OC12. Molecular chirality of DBAs (R and S) and monolayer chirality (RR(+) and SS( )) are indicated. S10

11 Figure S6: Supplementary STM images for phase IV of DBA-OC12. Molecular chirality of DBAs (R and S) and monolayer chirality (RR(+) and SS( )) are indicated. The green dashed circles and arrows in the bottom right image are used to outline two misalignments in the monolayer. S11

12 Table S1. Unit cell parameters of phase I~IV of DBA-OC12. S12

13 NOTE: In the following, all the STM images were acquired following the hot deposition protocol. S13

14 Table S2. A summary of the occurrence and surface coverage of different phases for each DBA. Note: a: phase III of DBA-OC13 was observed once in small domains, therefore was not included for analysis; b: since phase III and phase VI of DBA-OC16 coexist in a domain without boundaries, a total coverage of these two phases is provided (35.4 ± 6.3%). S14

15 Figure S7: DBA-OC11. a, b) Large scale STM images of DBA-OC11 at different concentrations. c) Distribution of monolayer structure at different concentrations. d) Unit cell parameters: a = 2.3 ± 0.2 nm, b = 4.4 ± 0.1 nm, γ = 105 ± 3 o. S15

16 Figure S8: DBA-OC13. a) Distribution of surface structures of DBA-OC13 at different concentrations. Large scale STM images of the monolayer of DBA-OC13 upon hot deposition have been reported in a previous study. 4 b) Unit cell parameters of two different phases of DBA-OC13. c) Two STM images presenting (+)-type and ( )- type phase III of DBA-OC13. Note that the probability of observing phase III is very low for DBA-OC13. S16

17 Figure S9: DBA-OC14. a-c) Large scale STM images of DBA-OC14 and d) distribution of different phases at different concentrations. e-h) Close-up images and unit cell parameters of phase I-IV of DBA-OC14. S17

18 Figure S10: DBA-OC13 & DBA-OC14. Molecular chirality (R and S) and monolayer chirality (RR( ), SS( ) and SS(+)) of phase III of a) DBA-OC13 and b) DBA-OC14. c) STM image showing (+)-rich and ( )-rich enantiomeric excess phase III of DBA-OC14. S18

19 Figure S11: DBA-OC15. a-c) Large scale STM images of DBA-OC15 and d) distribution of different phases at different concentrations. e) STM image showing two (+)-type structures that coexist without distinct grain boundary. S19

20 Figure S12: DBA-OC16. a) Large scale STM images and b) distribution of different phases of DBA-OC16 at different concentrations, c) unit cell parameters for each phase and d) two possible structural models for denselypacked phase VI. R and S-DBA are highlighted in blue and golden color, respectively. S20

21 ( )-type Figure S13: DBA-OC17. a-c) Large scale STM images and d) distribution of different phases of DBA-OC17 at different concentrations. e-f) Close-up images and unit cell lattice of all the four phases of DBA-OC17. Unit cell parameters of phase V are hard to be determined precisely as there no long range periodicity exists. S21

22 Figure S14: Monolayer chirality of phase V of DBA-OC17. a, b) Additional STM images and c) an idealized model of phase V of DBA-OC17. S22

23 Figure S15: DBA-OC20. STM images of DBA-OC20 at the concentration of M. The cross section analysis shows a variation in intermolecular distance, which we tentatively ascribe to the adsorption of four alkyl chains (red zone) or three alkyl chains (black zone) of each DBA molecule on surface. Only homochiral phase VI is observed. Note that small disordered areas can also be observed. Figure S16: In-situ measurement at 80 o C. In-situ STM images of the monolayer of DBA-OC13 at 80 o C at the octanoic acid/hopg interface. The concentration is M, and linear phase I can be clearly identified. This experiment validates that the monolayer structures observed by the hot deposition protocol are already formed at high temperature, and not during the cooling down process. S23

24 Figure S17: Long term heating experiment devised to validate the stability of monolayer formed upon hot deposition. STM images of the monolayer of DBA-OC15 at the air/hopg interface. 15 µl DBA-OC15 solution in octanoic acid at the concentration of M was applied on graphite surface and sequentially dried at 120 o C for approximately 1 h. Still the same structure is visualized for DBA-OC15, which can be considered as evidence for the excellent stability of DBA phases obtained by hot the deposition protocol. S24

25 Figure S18: Demonstration of the gain in packing density for a racemic lattice of DBA-OC13. S25

26 Figure S19: Demonstration of the variation in intermolecular distance and packing density caused by mismatched interdigitations of DBA-OC14. S26

27 Figure S20: Mixing of DBA-OC15 and DBA-OC16. STM images of a monolayer formed by an equimolar mixture of DBA-OC15 and DBA-OC16 at the octanoic acid/hopg interface upon hot deposition. The total concentration is M. Two different phases coexist on the surface. S27

28 Figure S21: Mixing of DBA-OC14 and DBA-OC15. STM images of a monolayer formed from an equimolar mixture of DBA-OC15 and DBA-OC14 at the octanoic acid/hopg interface upon hot deposition. The total concentration is M. Only one phase shows up, but both homochiral and enantiomeric excess monolayer chirality are revealed, indicating the occurrence of phase separation. The fact that DBA-OC15 and DBA-OC16 can be well mixed but DBA-OC15 and DBA-OC14 cannot is ascribed to an odd-even effect in the mixing behavior of DBAs, as illustrated in a previous study. 3 S28

29 Reference: 1. Tahara, K.; Furukawa, S.; Uji-I, H.; Uchino, T.; Ichikawa, T.; Zhang, J.; Mamdouh, W.; Sonoda, M.; De Schryver, F. C.; De Feyter, S.; Tobe, Y. Two-Dimensional Porous Molecular Networks of Dehydrobenzo[12]annulene Derivatives via Alkyl Chain Interdigitation. J. Am. Chem. Soc. 2006, 128, Tahara, K.; Yamaga, H.; Ghijsens, E.; Inukai, K.; Adisoejoso, J.; Blunt, M. O.; De Feyter, S.; Tobe, Y. Control and induction of surface-confined homochiral porous molecular networks. Nat. Chem. 2011, 3, Ghijsens, E.; Ivasenko, O.; Tahara, K.; Yamaga, H.; Itano, S.; Balandina, T.; Tobe, Y.; De Feyter, S. A Tale of Tails: Alkyl Chain Directed Formation of 2D Porous Networks Reveals OddEven Effects and Unexpected Bicomponent Phase Behavior. ACS Nano, 2013, 7, Cao, H.; Destoop, I.; Tahara, K.; Tobe, Y.; Mali, K. S.; De Feyter, S.; Complex Chiral Induction Processes at the Solution/Solid Interface. J. Phys. Chem. C 2016, 120, S29