Abstract
A series of new group 2 coordination polymers, MgL ={MgL(H2O)(DMF)0.75}∞, CaL = {CaL(DMF)2}∞, SrL = {SrL(H2O)0.5}∞ and BaL = {BaL(H2O)0.5}∞, were synthesized using a flexible benzimidazolone diacetic acid linker (H2L) in which the two carboxylic acid binding sites are connected to a planar core via {–CH2–} spacers that can freely rotate in solution. In a ‘curiosity-led' diversion from group 2 metals, the first row transition metal salts Mn2+, Cu2+ and Zn2+ were also reacted with L to yield crystals of MnL = {MnL(DMF)(H2O)3.33}∞, Cu3L2 = {Cu3L2(DMF)2(CHO2)2}∞ and ZnL = {ZnL(DMF)}∞. Crystal structures were obtained for all seven materials. All structures form as two-dimensional sheets and contain six-coordinate centres, with the exception of ZnL, which displays tetrahedrally coordinated metal centres, and Cu3L2, which contains square planar coordinated metal centres and Cu paddle-wheels. In each structure, the linker adopts one of two distinct conformations, with the carboxylate groups either cis or trans with respect to the planar core. All materials were also characterized by powder X-ray diffraction and thermogravimetric analysis.
Highlights
A series of new group 2 coordination polymers, MgL = {MgL(H2O)(DMF)0.75}∞, CaL = {CaL(DMF)2}∞, SrL = {SrL (H2O)0.5}∞ and BaL = {BaL(H2O)0.5}∞, were synthesized using a flexible benzimidazolone diacetic acid linker (H2L) in which the two carboxylic acid binding sites are connected to a planar core via {–CH2–} spacers that can freely rotate in solution
In SrL and BaL structures the linker carboxylate groups adopt a cisconformation and the two carboxylate groups both bind to the same metal node. This demonstrates the complex relationship between the linker flexibility and the metal ion used in the coordination polymer synthesis, and suggests that the larger cation size upon descending group 2 allows for chelate binding of the metal between two carboxylates and enables the linker to bind in the cis-conformation
All compounds were found to exist as 2D sheets with six-coordinate metal centres, except for ZnL, which showed tetrahedral 10 coordination around the metal centre, and Cu3L2, which exhibited both distorted paddle-wheels and square planar coordinated Cu2+
Summary
Phenylenediamine and sodium hydride were purchased from Sigma-Aldrich. Ethyl bromoacetate and anhydrous dimethylformamide (DMF) were purchased from ACROS Organics. All metal nitrate salts were purchased from Alfa Aesar. DMF and common laboratory solvents were purchased from Fisher Chemical. All reagents were used without any further purification
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
