Циклен

almost white to slightly yellow crystalline powder, soluble in methanol, ethanol, dmso and other organic solvents, derived from stephania cepharantha.

Cyclen is an azamocrocycle, which can be used in the development of fluorescent nanosensors for the detection of metal ions.

Cyclen (1,4,7,10-tetraazacyclododecane) is a macrocyclic aza analogue of the crown ether 12-crown-4. Cyclen compounds are capable of selectively binding cations and are used as a ligand with chemicals used in MRI contrast (as well ass other imaging) agents.

Cyclen is a microcyclic tetramine that can be used as a ligand that forms a co-ordination linkage with the surface metal cations. It can be used as a synthetic precursor. It can be prepared by S-alkylation of dithiooxamide with an excess amount of bromoethane.

Some syntheses exploit the Thorpe-Ingold effect to facilitate ring-formation. Illustrative is the reaction of the deprotonated tosylamides with ditosylates:
TsN(CH2CH2NTsNa)2 + TsN(CH2CH2OTs)2 → (TsNCH2CH2)4
The resulting macrocycle can be deprotected with strong acid. Base gives the tetramine.
High dilution conditions result in a low reaction rate penalty and this disadvantage is removed in an alternative procedure starting from triethylenetetraamine and dithiooxamide to a bisamidine – also a bis(imidazoline) – followed by reduction and ring expansion with DIBAL.

In one study cyclen is covalently bonded through a propylene molecular spacer to adenine and chelated with zinc diperchlorate. This complex is able to selectively bind uracil and uridine in a 1:2 ratio both through the adenine part and cyclen part of the molecule as evidenced by mass spectrometry.
wiki/Cyclen