Enhanced hydrolytic stability of self-assembling alkylated two-dimensional covalent organic frameworks.

The stability and bulk properties of two-dimensional boronate ester-linked covalent organic frameworks (COFs) were investigated upon exposure to aqueous environments. Enhanced stability was observed for frameworks with alkylation in the pores of the COF compared to nonalkylated, bare-pore frameworks. COF-18Å and COF-5 were analyzed as "bare-pore" COFs, while COF-16Å (methyl), COF-14Å (ethyl), and COF-11Å (propyl) were evaluated as "alkylated-pore" materials.

Tristability arising from singlet-triplet and quartet spin states for dimeric Co(II)salen.

The magnetic behavior of N,N'-ethylenebis(salicylideniminato)cobalt(II) (Co(II)Salen, 1) has been reinvestigated and reveals spin-crossover behavior above 295 K. It has a singlet ground state and a triplet excited state at 30 K (21 cm(-1); 60 cal/mol) above the ground state, and at a higher temperature spin crossover to the quartet, a second excited state occurs.