DCDAPH (Compound 2c) is a novel smart NIRF probe for detection of β-amyloid ( Aβ ) plaques (λ ex /λ em =597/665 nm in PBS). DCDAPH shows high affinity for Aβ aggregates ( K i =37 nM, K d =27 nM). DCDAPH shows good blood brain barrier permeation and can meet most of the requirements for the detection of Aβ plaques both in vitro and in vivo.