Synthesis of Novel Chiral and Acentric Coordination Polymers by the Reaction of Zinc or Cadmium Salts with Racemic 3‐Pyridyl‐3‐aminopropionic Acid

Under hydrothermal (solvothermal) reaction conditions chiral compounds 1 , 2 , and 3 and one acentric compound 4 were obtained by the reaction of Zn 2+ or Cd 2+ with racemic 3‐(3‐pyridyl)‐3‐aminopropionic acid ( rac ‐HPAPA). Compounds 1 and 2 crystallized in chiral space group P 2 1 2 1 2 1 . At 105 °C, racemic 3‐pyridyl‐3‐aminopropionic acid ( rac ‐HPAPA) reacted with Zn(ClO 4 ) 2 ⋅ 6 H 2 O and dehydrogenated in situ to form the first chiral coordination polymer [Zn{( E )‐3‐C 5 H 4 NC(NH 2 )CHCOO}]ClO 4 ( 1 ) with a β‐dehydroamino acid. Beyond 120 °C, the reaction of rac ‐HPAPA with Zn(ClO 4 ) 2 ⋅ 6 H 2 O deaminates in situ to form chiral coordination polymer [Zn{( E )‐3‐C 5 H 4 NCHCHCOO}(OH)] ( 2 ). At relatively low temperatures (70 °C), the solvothermal reaction of Zn(NO 3 ) 2 ⋅ 6 H 2 O with rac ‐HPAPA in methanol does not lead to any change in the ligand and results in the formation of a chiral ( P 2 1 2 1 2 1 ) coordination polymer [Zn(papa)(NO 3 )] ( 3 ). The same reaction of Cd(ClO 4 ) 2 ⋅ 6 H 2 O with HPAPA also does not lead to any change in ligand and results in the formation of noncentric ( Cc ) coordination polymer [Cd(papa)(Hpapa)]ClO 4 ⋅ H 2 O ( 4 ). The network topology of both 1 and 3 is 10,3a, while 2 has a diamondoid‐like (KDP‐like, KDP=potassium dideuterophosphate) network. Particularly interesting from a topological perspective is that 4 has an unprecedented three‐dimensional network. Compounds 1 , 2 , 3 , and 4 are all second harmonic generation (SHG) active with 1 exhibiting the strongest response, while only 4 also displays good ferroelectric properties.