Manipulation of Origin of Life Molecules: Recognizing Single Molecule Conformations in β-Carotene and Chlorophyll-a - β-Carotene Clusters.

Carotenoids and chlorophyll are essential parts of plant leaves and are involved in photosynthesis; a vital biological process responsible for the origin of life on Earth. Here, we investigate how β-carotene and chlorophyll-a form mixed molecular phases on a Au(111) surface using low temperature scanning tunneling microscopy and molecular manipulation at the single molecule level supported by density functional theory calculations. By isolating individual molecules from nanoscale molecular clusters with a scanning tunneling microscope tip, we are able to identify five β-carotene conformations including a structure exhibiting a 3-dimensional conformation. Furthermore, molecular resolution images enable direct visualization of β-carotene-chlorophyll-a clsuters with intimate structural details highlighting how they pair: β-carotene preferentially positions next to chlorophyll-a and induces switching of chlorophyll-a from straight to several bent tail conformations in the molecular clusters.