Born in Constantinople of Chiot parents, Syngros was one of the founders of the Bank of Constantinople along with Stephanos Skouloudis. Syngros married Iphigenia Mavrokordatou of the wealthy merchant Mavrokordatos family; they never had any children. They moved to Athens in 1871 where Syngros planned to found a new bank. Buying land from the widow of Dimitrios Rallis, Syngros engaged the well-known Athenian architect Nikolaos Soutsos who built his home based on plans by the German Ernst Ziller, across from the Royal Palace. Today the mansion is the headquarters of the Greek Foreign Ministry, having been left to the state by his widow.
In Athens, Syngros founded the Pistotiki Bank (Bank of Credit). He also became involved in numerous works of public philanthropy, including building an avenue from the Royal Palace to the bay at Faliro (named after him today, Syngrou Avenue) and he was responsible for completing the Corinth Canal, one of the great feats of engineering in Greece, in 1893.
Syngros died in Athens in 1899.