He was also appointed Apostolic Nuncio for the city of Florence, which was then the capital of the Grand Duchy of Tuscany.

When the proclamation of Papal Infallibility caused a schism in the Armenian Catholic Church, he was sent to Istanbul to convince Sultan Abdülaziz that the Vatican's position was correct and ensure that Patriarch Anthony Petros IX Hassun would also be recognized as infallible.

He was created a Cardinal on 22 December 1873 and, the following month, received the title of "Santa Maria in Trastevere".

At the Papal conclave held after the death of Pius IX, he was a supporter of Cardinal Pecci, who was elected and took the name of Leo XIII.

He had already made some diplomatic approaches to Bavaria and Prussia when he died suddenly, from malaria (although some suspected poisoning).