I am posting this on behalf of a friend, as English is not his native tongue.
Here are the facts that he has:
Dr. Carl Eisenstein was born near Vienna (Baden bei Wien) on January 31, 1878.
They had two children, Fritz (Friedrich) born September 2nd, 1909, and Franziska born on September 7th, 1912, probably born also in the Czech Republic in Königinhof an der Elbe (Dvůr Králové nad Labem).
Ph. Dr. chemist Carl Eisenstein had an older brother, also a Chemist: Dr. Alfred Eisenstein, born November 8th, 1876, died August 18th, 1949. He is buried at the Kessler Israel cemetery in West Haven, Connecticut, USA. He was married to Gertrud, nee Heller, born in Podersam on May 11th, 1894. Gertrud Eisenstein died in January 1990 at the age of 95, residing in Jamaica, Queens County New York. They left Austria on November 22nd, 1938 to the U.S. This couple had no children.
Brooklyn, New York, USA