2,2',2''-(10-(2-(6-(1,5-bis(3-((2R,5S,8S,14R)-5-(3-guanidinopropyl)-14-(4-hydroxybenzyl)-1-methyl-8-(naphthalen-2-ylmethyl)-3,6,9,12,15-pentaoxo-1,4,7,10,13-pentaazacyclopentadecan-2-yl)propylamino)-1,5-dioxopentan-3-ylamino)-6-oxohexylamino)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetic acid