An ultrasonic reaction of Ag₂O, 4,4′-bipyridine (bipy) and (2S, 3R)-3-amino-2-hydroxybutanoic acid (L-Thr) gives an unexpected Ag(I) supramolecular framework, {[Ag₃(bipy)₃(cahba)]·HCO₃·10H₂O}_n (1), in which the (2S, 3R)-3-(carboxyamino)-2-hydroxybutanoic acid (H₂cahba) is a carbamate derivative of L-Thr, obtained via in situ transformation of amino group of L-Thr into carbamate by means of CO₂ uptake.