Is it permissible to take out a loan from an interest-based bank to purchase an apartment on the first floor, given the inability to sell the current apartment on the fifth floor, and the absence of Islamic banks?

It is impermissible to borrow with usury unless there is a recognized necessity, and what has been mentioned does not constitute a necessity. Usury is among the grave sins. Allah Almighty says: "O you who have believed, fear Allah and give up what remains [due to you] of usury, if you should be believers. And if you do not, then be informed of a war [against you] from Allah and His Messenger." The Prophet, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses. Whoever fears Allah, He will make his matter easy and provide for him from where he does not expect.