Thin film fabrication of 2D layered organic-inorganic hybrid perovskites (2D-OIHPs) for spintronic applications has been attempted using solutionbased process like Langmuir-Blodgett technique. However, monolayer or few-layered 2D magnets are not yet realized, even though a wide spectrum of 2D Ruddlesden-Popper (RP) OIHPs are known as quasi-2D Heisenberg magnets in bulk compounds. Here, chemical exfoliation by solvent engineering is applied to successfully synthesize large-sized, few unit-cell-thick 2D RP-OIHPs. Comprehensive structural characterization reveals that binary co-solvents with high relative polarity in spin coating technique are the most effective among nine kinds of solvents. Above all, this enables few-layered 2D RP-OIHP ultrathin films sustaining their intrinsic magnetic order. It is found that XY-like magnetic anisotropy driven by Jahn-Teller effect responsible for ferromagnetism in seven-layered (C 6 H 5 CH 2 CH 2 NH 3) 2 CuCl 4 ultrathin films remains very robust, whereas Ising-like dipolar anisotropy responsible for canted antiferromagnetism in ten-layered (C 6 H 5 CH 2 CH 2 NH 3) 2 MnCl 4 ultrathin films is greatly reduced. It is expected that ferromagnetism even at monolayer limit should be possible by means of further sophisticated solvent engineering as long as Jahn-Teller effect is active. The chemical exfoliation using solvent engineering unambiguously can bring about a new breakthrough in the development of 2D RP-OIHP van der Waals magnets for ultrahigh energyefficient spintronic, opto-spintronic devices.

C 28 H 40 MnN 6 O 12 S 2 , monoclinic, P21/c (no. 14), a = 6.211(5) Å, CCDC no.: 1446507The crystal structure is shown in the gure. Tables 1-3 contain details of the measurement method and a list of the atoms including atomic coordinates and displacement parameters. Source of materialMnCl 2 . 4H 2 O (0.2976 g) was added to a solution of C14H14N 3 NaO 3 S (0.491 g) in methanol (200 mL) and the mixture was slowly evaporated. Small red-brown crystals were obtained approximately after a week. Experimental detailsAll H atoms were located in a di erence Fourier map. Carbon-bound hydrogen atoms are riding on the parent atom, whereas the oxygen-bound hydrogen atom positions are re ned. H atoms at methyl group were re ned with U iso (H) = 1.5Ueq(C).

Various morphologies of Cu 2 S and Cu 2 MoS 4 were synthesized from an octahedral Cu 2 O template in the presence of various concentrations of sodium molybdate and thioacetamide by carrying out solvothermal reactions in an ethylene glycol solvent. The morphology varied from hollow octahedral Cu 2 S structures, through small pieces of P-Cu 2 MoS 4 , and finally to thin square-like plates of I-Cu 2 MoS 4 , depending on the concentrations of sodium molybdate and thioacetamide. The XRD data indicated that the Cu 2 MoS 4 structural phases changed from P42m to I42m the concentrations of sodium molybdate and thioacetamide increased.

C 28 H 40 N 6 NiO 12 S 2 , monoclinic, P21/c (no. 14), a = 6.202(1) Å, b = 7.126(1) Å, c = 38.499(2) Å, β = 91.258(2)°, V = 1701.1(4) Å 3 , CCDC no.: 1560153The cation and the anion forming the title crystal structure are shown in the figure. Tables 1 and 2 contain details of the measurement method and a list of the atoms including atomic coordinates and displacement parameters. Source of materialsNiCl 2 ·6H 2 O (0.364 g) was added to a solution of C14H14N 3 NaO 3 S (0.491 g) in methanol (200 mL) and the mixture was slowly evaporated. Small red-brown crystals were obtained after approximately 1 week.