Supplementary Information
On-Surface Growth of Transition-Metal Cobalt Nanoclusters Using 2D
Crown-Ether Array
Toyo Kazu Yamada1,2*, Ryohei Nemoto1, Fumi Nishino1,5, Takuya Hosokai3, Chi-HsienWang4, Masaki Horie4, Yuri Hasegawa5, Satoshi Kera5, and Peter Krüger1,2
1. Department of Materials Science, Chiba University, 1-33 Yayoi-Cho, Inage-ku, Chiba 263-8522, Japan.
2. Molecular Chirality Research Centre, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
3. National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology,Tsukuba Central 2, 1-1-1, Umezono, Tsukuba, Ibaraki 305-8568, Japan
4. Department of Chemical Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Road, Hsinchu,
30013, Taiwan
5. Institute for Molecular Science, Myodaiji, Okazaki 444-8585 Japan

Author Information,
Corresponding Author: Toyo Kazu Yamada *E-mail: toyoyamada@faculty.chiba-u.jp
Version 2023.11.30

RSC style: Chemical ScienceSupplementary Notes(1) Home-Built Low-Temperature UHV STM Setup.
STM measurements were performed using home-built UHV-STM equipment consisting of STM,
preparation, and deposition chambers. The base pressures of each chamber were below 5.0 × 10−8 Pa,
2.0×10-8 Pa, and 1.0×10-7 Pa, respectively. The Cu(111) was cleaned in the preparation chamber, andBrCR molecules were deposited in the deposition chamber. Samples and STM tips were transferred
between chambers using transfer rods without breaking the UHV. Gate valves separated each chamber.
A UHV cryostat (CryoVAC) in the STM chamber was used to cool down the STM setup.

(2) UHV ARPES / LEED Setup.
All ARPES measurements were performed at 80 K using an ultralow-background, high-sensitivity
ARPES apparatus with a hemispherical electron energy analyzer (MBS A-1) and twin
monochromators (MBS TM-1) for two wavelength regions as setup. He-Iα (hν = 21.218 eV) radiation
was performed using a high-density plasma lamp (MBS L-1) combined with an Al filter. LEED witha multichannel plate (MCP) equipped in the preparation chamber was used to detect weak electron
signals from the monolayer molecular film. To avoid damage to the deposited molecular film, we used
10−50 eV beam energy. The sample current was below 0.1 μA during LEED measurements.

Figure S1, 1H NMR spectrum (500 MHz, CDCl3, r.t.) of BrCR.

cbaH2O

CHCl3abc
AcetoneFig. S1. 1H NMR spectrum (500 MHz, CDCl3, r.t.) of BrCR.

Figure S2, Low- and high-resolution field-desorption mass spectra of BrCR.

Centroid [MS: 0.3811-0.7143] / 2022032914-hsin171 / FD+(eiFi) / /6x10(1460633)

675.8

1.50

1.25

Intensity

1.00

0.75

0.50

0.25

0.00
250

5007501000

1250

1500m/zCentroid [MS: 0.6428-0.7027] / 2022083042-258 / FD+(eiFi) / /4x10(10434)

675.7954
1.00

Intensity

0.75

673.7978677.7930

0.50

676.8006

0.25

671.8005

674.8049

678.8005

0.00
665670

675

680

685

m/z

Fig. S2. Low- and high-resolution field-desorption mass spectra of BrCR. The peak at m/z = 671.8005
corresponds to [C20H20Br4O6]+ = 671. 79989 (error = 0.96 ppm).

Figure S3, Single-crystal X-ray crystallographic structure of BrCR.

Fig. S3. Single-crystal X-ray crystallographic structure of BrCR with ellipsoid plot with 50% probability.
Hydrogen atoms are omitted for simplification.

Figure S4, ARPES spectra using He-Ⅱ light source (40.8 eV).
Figure S1b shows the difference between spectra in Fig. S1a before (blue line) and after (red line) theCo deposition on the Br-CR film on Cu(111).

aregion III region II region I
HeII := 40.8 eVbFig. S4. ARPES spectra using He-Ⅱ light source. (a) ARPES spectra obtained from the Cu(111) substrate(black line), 1 ML BrCR film on Cu(111) (blue line), and 0.57 ML Co on 1 ML BrCR film (red line). (b)Difference between the blue and red lines in (a).

Figure S5, ARPES, E-k maps.
Figure S5 shows ARPES E-k maps obtained on 0.57 MLs Co / Cu(111), 1 ML Br-CR film / Cu(111),
and 0.57 MLs Co / 1 ML Br-CR film / Cu(111). Weak, faint features of parabolic bands caused byforming the Co/crown nanoclusters are found in Fig.S2c. It could be interesting to reveal the origin ofthe quantum confinement at the complicated interface. However, it is necessary to repeat the ARPES
experiments for a well-oriented system to discuss in detail [Matsuda, I.; Tanikawa, T.; Hasegawa, S.;
Yeom, H. W.; Tono, K. and Ohta, T. Quantum-Well States in Ultra-Thin Metal Films on
Semiconductor Surfaces. e-J. Surf. Sci. Nanotech. 2004, 2, 169-177].

aCo / Cu(111)bc

Br-CR / Cu(111)

Co / Br-CR/Cu(111)HOMO−1.48 eVHeI := 21.218 eV

HeI := 21.218 eV

HeI := 21.218 eVFig. S5. ARPES maps using the He-I light source obtained on (a) 0.57 MLs Co / Cu(111), (b) 1 ML BrCRfilm / Cu(111), and (c) 0.57 MLs Co / 1 ML BrCR film / Cu(111).

Figure S6,Figure S6a shows a LEED image obtained with an incident beam energy of EB = 36.9 eV from theBrCR regular arrangement before Co deposition. LEED with a multichannel plate (MCP) equipped in
the preparation chamber was used to detect weak electron signals from the monolayer molecular film.
To avoid damage to the deposited molecular film, we used 10−50 eV beam energy. The sample current
was below 0.1 μA during LEED measurements. Six-fold symmetric spots (blue circles) with satellite
spots indicate three-fold domains of periodic BrCR arrays in agreement with the previous study [WellOrdered Monolayer Growth of Crown-Ether Ring Molecules on Cu(111) in Ultra-High Vacuum: A
STM, UPS, and DFT Study, Nemoto, R.; Krueger, P.; Hartini, A. N. P.; Hosokai, T.; Horie, M.; Kera,S.; Yamada, T. K. The Journal of Physical Chemistry C 2019, 123, 18939-18950.]. The LEED image

LEED & ARPES results
before Co deposition Br-CR / Cu(111)ba(00)(00)

EB = 36.9 eV

EB = 106.1 eV

after Co deposition Br-CR / Cu(111)dc(00)EB = 36.9 eV(00)EB = 104.1 eV

Figure S6. LEED results obtained on the surface before and after the 0.57 MLs Co deposition on the 1 ML
BrCR film on Cu(111). (a-d) LEED images measured before (a,b) and after (c,d) the Co deposition. Blueand red dot circles denote LEED spots originated from the (7 × 4) BrCR array and the fcc-Cu(111) symmetry,respectively. The (00) spot position is marked by the while circle.

in Fig. S6b was obtained from the same surface with EB = 106.1 eV, and the sample surface was gently
tilted to see the fcc-Cu(111) spots marked by the red circles. Here, the incident (00) spot is observedon the left-hand side. Fig. S6c and Fig. S6d were obtained after the Co deposition. The LEED patterns
derived from the BrCR molecule were about to disappear, but the substrate fcc-Cu(111) spots wereconfirmed. These LEED results indicate enhancement of the BrCR array disordering due to the CoBrCR nanocluster formation, which is in good agreement with the nanocluster formation observed inthe STM results in Fig.1. Here, we deposited 57 times more Co atoms on the BrCR film. Then, thecomplete BrCR film could change to metal-organic nanoclusters (see also Fig. S7).

Figure S7

NCo > NBrCR
Topographic image

Current image

Originally
Br-CR array
Figure S7. STM topographic image of a complete Co-BrCR nanocluster formation on Cu(111).

Figure S8100dI/dV (pA/V)

80

BrCRHOMO60BrCRLUMO

40200−2−1012E - EF (eV)Figure S8. Differential conductance dI/dV curve obtained on the ordered pristine BrCR film on Cu(111):Vs ＝ －2.5 V, I ＝ 1 nA. Two peak shoulders indicate HOMO and LUMO energy positions.