novel fluorescent markers of formula i : are disclosed herein , wherein x and y are independently or together absent or are independently selected from r and r 1 are independently selected from h and alkyl ; ar is phenyl or heteroaryl ; l is absent or a spacer selected from the group consisting of — nh —; — n nh —; — nhso 2 —; — n nhco —; - nhco —; — n nhso 2 —; - nhso 2 —; — conh n nhco —; — conhnhco —; — nhco n nhco —; — nhconhco —; — n so 2 nh —; - so 2 nh —; — n nhcsnh —; - nhcsnh —; — cr ═ cr 1 —; — c ≡ c —; — n n ═ ch —; - n ═ ch —; — n ═ ch —; — n ═ ch -; n is an integer ranging from 1 to 5 ; f is a fluorophore selected from the group consisting of fluorescein , rhodamine , eosin , thionine , safranin , coumarin , methoxycoumarin , dansyl , bodipy and bodipy derivatives ; and wherein x , y and l may be positioned in a 1 , 3 , 5 ; 1 , 2 , 3 ; 1 , 3 , 4 or in a 3 , 4 , 5 configuration respectively .