Ligand‐dependent aggregation‐enhanced photoacoustic of atomically precise metal nanocluster
Changlin Zhou,
Meng Wang,
Qiaofeng Yao,
Yu Zhou,
Chuantao Hou,
Jianfei Xia,
Zonghua Wang,
Jishi Chen,
Jianping Xie
Affiliations
Changlin Zhou
College of Chemistry and Chemical Engineering, Shandong Sino‐Japanese Center for Collaborative Research of Carbon Nanomaterials Instrumental Analysis Center of Qingdao University Qingdao University QingdaoP. R. China
Meng Wang
College of Chemistry and Chemical Engineering, Shandong Sino‐Japanese Center for Collaborative Research of Carbon Nanomaterials Instrumental Analysis Center of Qingdao University Qingdao University QingdaoP. R. China
Qiaofeng Yao
Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, School of Science Tianjin University TianjinP. R. China
Yu Zhou
College of Chemistry and Chemical Engineering, Shandong Sino‐Japanese Center for Collaborative Research of Carbon Nanomaterials Instrumental Analysis Center of Qingdao University Qingdao University QingdaoP. R. China
Chuantao Hou
College of Chemistry and Chemical Engineering, Shandong Sino‐Japanese Center for Collaborative Research of Carbon Nanomaterials Instrumental Analysis Center of Qingdao University Qingdao University QingdaoP. R. China
Jianfei Xia
College of Chemistry and Chemical Engineering, Shandong Sino‐Japanese Center for Collaborative Research of Carbon Nanomaterials Instrumental Analysis Center of Qingdao University Qingdao University QingdaoP. R. China
Zonghua Wang
College of Chemistry and Chemical Engineering, Shandong Sino‐Japanese Center for Collaborative Research of Carbon Nanomaterials Instrumental Analysis Center of Qingdao University Qingdao University QingdaoP. R. China
Jishi Chen
College of Chemistry and Chemical Engineering, Shandong Sino‐Japanese Center for Collaborative Research of Carbon Nanomaterials Instrumental Analysis Center of Qingdao University Qingdao University QingdaoP. R. China
Jianping Xie
Department of Chemical and Biomolecular Engineering National University of Singapore Singapore
Abstract Atomically precise metal nanoclusters (MNCs), as a potential type of photoacoustic (PA) contrast agent, are limited in application due to their low PA conversion efficiency (PACE). Here, with hydrophilic Au25SR18 (SR = thiolate) as model NCs, we present a result that weakly polar solvent induces aggregation, which effectively enhances PA intensity and PACE. The PA intensity and PACE are highly dependent on the degree of aggregation, while the aggregation‐enhanced PA intensity (AEPA) positively correlates to the protected ligands. Such an AEPA phenomenon indicates that aggregation actually accelerates the intramolecular motion of Au NCs, and enlarges the proportion of excited state energy dissipated through vibrational relaxation. This result conflicts with the restriction of intramolecular motion mechanism of aggregation‐induced emission. Further experiments show that the increased energy of AEPA originates from the aggregation inhibiting the intermolecular energy transfer from excited Au NCs to their surrounding medium molecules, including solvent molecule and dissolved oxygen, rather than restricting radiative relaxations. This study develops a new strategy for enhancing the PA intensity of Au NCs, and contributes to a deeper understanding of the origin of the PA signal and the excited state energy dissipation processes for MNCs.
