Interpenetration is common in the synthesis of porous coordination polymers(PCPs)/metal organic frameworks(MOFs).1 A less common and often more complicated sub-class of interpenetration is self-penetration,2 Self-penetration has been hard to predict,to classify or even to rationalize in hindsight.Here,we suggest that the use of bent tritopic carboxylate ligands engender a higher probability of self-penetration in PCPs.The particular tritopic carboxylate ligands used in this work contains two moieties: i)an approximately co-planar pyridinium dicaboxylate(delineated as Part A),and ii)an N-alkyl carboxylate or benzoate(delineated as Part B)(Chart 1).The C-C-N angle of ca.109.5° around the methylene linkage dictates the angle of Part A relative to the second rod-shaped dipyridyl ligand,precluding parallel and perpendicular alignment,but making an irregular angle through which the dipyridyl rod can thread(Chart 1).Complexes {[Cu3(Cmdcp)2(azopy)3(H2O)2]·(NO3)2}n(1,3D self-penetrating),{[Cu(Cmdcp)(bpe)(H2O)3]·3H2O}n(2,1D chain),{[Cu3(HCbdcp)4(azopy)3(H2O)2]·Cbdcp}n(3,2D grid)and {[Cu3(Cbdcp)2(bpe)3(H2O)3]·(NO3)2}n(4,3D self-penetrating)were synthesized from the reactions of Cu(NO3)2 with deprotonated pyridinium carboxylate in the presence of NaOH,followed by addition of the dipyridyl ancillary ligand.Activated sample of 4 has a Brunauer-Emmett-Teller(BET)surface area of 129 m2·g–1.