2d 21In this work, we introduce helical chirality into 2D COFs using confurationally stable enantiopure and racemic [5]helicenes as linkers inErek Erek 21 menurut buku seribu tafsir mimpi 2D 3D 4D bergambar dan primbon melambangkan sosok pelacur umum, sedangkan kode alam angka 21