Fig. 2: Single crystals of CityU-17 and CityU-18.

a Growth of single-crystal CityU-17 and CityU-18. b Optical microscopic image for CityU-17. c Partial enlargement of CityU-17 to clarify the connection in the 2D framework. d Single-crystal structure of CityU-17. e Optical microscopic image for CityU-18. f, Partial enlargement of CityU-18 for clarifying the connection in the 2D framework. g Single-crystal structure of CityU-18. Hydrogen atoms are omitted for clarity.