No, Constantinople was the capital of the Byzantine Empire. The Byzantine Empire was the Eastern split of the Roman Empire and later ruled from Rome through Southeastern Europe and Asia Minor, down to Egypt and across North Africa.
The capital of the Roman empire was Rome and later Ravinia, in the West. In the East it was Constantinople.
It was the capital of Eastern Roman Empire, which was later called by the historians Byzantine Empire to differentiate it from the Roman Empire. Constantinople was named by the Roman emperor Constantine the First after himself but there was already a city at that location called "Byzantium". However, the people living there just usually called their city "Istanbul", which means "in this city". Today, the city is officially called Istanbul. It is the largest and most famous city of Turkey and was the capital city of the Ottoman empire until the foundation of the Turkish republic in 1922. The capital was then moved to Ankara.
Constantinople
The Eastern Roman Empire or Byzantium, capital city - Constantinople (nowadays - Istambul).
Constantinople was the capital city of the Eastern Roman Empire, named so after Constantine the Great. It was not an empire.
Your question is very unclear. Constantinople was a Roman city, it was the imperial capital of the eastern part of the Roman Empire (the imperial capital of the western part of the Roman Empire was Milan).
During the last days of the Eastern Roman Empire, the modern city of Istanbul was called Constantinople. The name Constantinople was given to the city by the Roman Emperor Constantine the Great in 330 AD when he made it the new capital of the Roman Empire. It remained the capital of the Byzantine Empire until it was captured by the Ottoman Empire in 1453 and renamed Istanbul.
The Emperor Constantine the Great (also known as Constantine I) moved the capital of the old Roman Empire to the Ancient Greek city in the East called Byzantium, and renamed this city as "Constantinople - the New Rome" in the year 330 AD. Constantinople remained the capital of the New Roman (or Eastern Roman) Empire until the year 1453 AD.
Constantinople
Byzantium, later renamed Constantinople after him (polis = city in Greek, the language of the Eastern Roman Empire).
Constantinople was named after the Roman Emperor Constantine. After the fall of the Roman Empire it became a predominantly Muslim and was renamed Istanbul which is in Turkey.
Constantinople was the capital of the Byzantine/Eastern Empire. It wasn't the capital of the whole empire, but it was a major city for sure.