Study On The Ultrafast Nonlinear Optical And Chiroptical Properties Of Multicolor Small Molecule

Nonlinear optics is an important branch of nonlinear physics and modern optics.It has broad applications including laser technology,optical communications,information storage and so on,which indicates that it has great application and scientific significance.Chiral fluorescent molecules usually exhibits both the circular dichroism and circularly polarized luminescence,which makes these molecules have great applications value in 3D information storage,all-optical modulation and so on.Therefore,the design and synthesis of organic molecules with excellent nonlinear optical and chiroptical have important application in many fields.In the thesis,the nonlinear optical properties of blue,green and red molecules are studied by utilizing Z-scan,multiphoton fluorescence spectroscopy and femtosecond transient absorption spectroscopy.Their multiphoton absorption,excited-state absorption behaviors,and intersystem crossing and their applications in fluorescence bioimaging,optical limiting,and photodynamic therapy have been investigated.The detailed research contents are included as follows.(1)We designed and synthesized a series of blue phenylacetylene molecules and studied their nonlinear optical behaviors including two-,three-and four-photon absorption.The multiphoton absorption cross-section of these molecules was among the largest values reported up to now.Moreover,these molecules had efficient intersystem crossing.Their applications in multiphoton fluorescence imaging and photodynamic therapy have been demonstrated successfully.In addition,we modified these molecules with natural amino acids,which displayed efficient chiroptical behaviors.(2)We studied the two-photon absorption of a commercial green emissive dye,i.e.,3-aminophthalic acid.Although the molecule displays relatively weak two-photon absorption,it exhibits high fluorescence quantum yield,long fluorescence lifetime and efficient intersystem crossing.We successfully apply this molecule in two-photon fluorescence lifetime imaging and photodynamic therapy.(3)We synthesized one stilbene dye with bright red emission in highly polarsolvents.This molecule shows excellent two-and three-photon absorption.Additionally,this molecule have sucessfully used in optical limiting and two-photon fluorescence imaging.