We first explore the phase emergence behavior of the BA-based quasi-2D HPs -a RP-type spacer with a short alkyl chain (Figure ). At low 3D ratios (<10%), in addition to the dominant emergence of low-n 2D HPs (e.g., n=1-3; PL peaks <600 nm), considerable PL signals ranging 600-700nm associated with high-n phases (e.g., n≥4) are observed, though their synthesizability are comparatively unfavorable in thermodynamics than that of the low-n counterparts . Presumably, these high-n HPs are kinetic products, given the low molecular weight of BA and the lower emergences of such phases in other combinatorial libraries with ThEA and PEA spacers at this compositional range (vide infra); it is likely attributed to the higher diffusivity of BA in the precursor system and lower degree of inter-molecular interaction than other spacer cations. Note that, further increases in the 3D ratio (up to ~25%) counterintuitively suppress the crystallization of the high-n HPs that require 3D HP building blocks, again corroborating that the emergence of these phases is thermodynamically unfavorable in such compositional range.