Arundhati Deshmukh

All Publications

• Tuning the Quantum-Well Structure of Single-Crystal Layered Perovskite Heterostructures. Journal of the American Chemical Society Deshmukh, A. P., Chen, Y., Cleron, J. L., Tie, M., Wen, J., Heinz, T. F., Filip, M. R., Karunadasa, H. I. 2025

  Abstract

  Single-crystal layered perovskite heterostructures provide a scalable platform for potentially realizing emergent properties recently seen in mechanically stacked monolayers. We report two new layered perovskite heterostructures M2(PbCl2)(AMCHC)2(PbCl4)·2H2O (1_M where M = Na+, Li+; AMCHC = +NH3CH2C6H10COO-) crystallizing in the chiral, polar space group C2. The heterostructures exhibit alternating layers of a lead-chloride perovskite and an intergrowth comprising corner-sharing PbCl4(η2-COO)2 polyhedra with bridging equatorial chlorides and terminal axial oxygen ligands. Small alkali metal cations and water molecules occupy the cavities between the polyhedra in the intergrowth layer. The heterostructures display wide bandgaps, two closely spaced excitonic features in their optical spectra, and strong second harmonic generation. The calculated band structure of 1_Na features a Type-I quantum-well structure, where the electron-hole correlation function corresponding to the lowest excited state points to electron-hole pairs localized within a single inorganic layer (intralayer excitons), as seen in typical layered halide perovskites. In contrast, calculations show that 1_Li adopts a Type-II quantum-well structure, with electrons and holes in the lowest excited state residing in different inorganic layers (interlayer excitons). Calculations on model complexes suggest that these changes in band alignment, between Type-I and Type-II quantum-well structures, are driven by the placement of the alkali metal and the orientation of the water molecules, changing the electrostatic potential-energy profiles of the heterostructures. Thus, this study sets the stage for accessing different alignments of the perovskite and intergrowth bands in bulk perovskite heterostructures that self-assemble in solution.

  View details for DOI 10.1021/jacs.5c08391

  View details for PubMedID 41133977

• De novo design of proteins housing excitonically coupled chlorophyll special pairs NATURE CHEMICAL BIOLOGY Ennist, N. M., Wang, S., Kennedy, M. A., Curti, M., Sutherland, G. A., Vasilev, C., Redler, R. L., Maffeis, V., Shareef, S., Sica, A. V., Hua, A., Deshmukh, A. P., Moyer, A. P., Hicks, D. R., Swartz, A. Z., Cacho, R. A., Novy, N., Bera, A. K., Kang, A., Sankaran, B., Johnson, M. P., Phadkule, A., Reppert, M., Ekiert, D., Bhabha, G., Stewart, L., Caram, J. R., Stoddard, B. L., Romero, E., Hunter, C., Baker, D. 2024

  Abstract

  Natural photosystems couple light harvesting to charge separation using a 'special pair' of chlorophyll molecules that accepts excitation energy from the antenna and initiates an electron-transfer cascade. To investigate the photophysics of special pairs independently of the complexities of native photosynthetic proteins, and as a first step toward creating synthetic photosystems for new energy conversion technologies, we designed C2-symmetric proteins that hold two chlorophyll molecules in closely juxtaposed arrangements. X-ray crystallography confirmed that one designed protein binds two chlorophylls in the same orientation as native special pairs, whereas a second designed protein positions them in a previously unseen geometry. Spectroscopy revealed that the chlorophylls are excitonically coupled, and fluorescence lifetime imaging demonstrated energy transfer. The cryo-electron microscopy structure of a designed 24-chlorophyll octahedral nanocage with a special pair on each edge closely matched the design model. The results suggest that the de novo design of artificial photosynthetic systems is within reach of current computational methods.

  View details for DOI 10.1038/s41589-024-01626-0

  View details for Web of Science ID 001237780900001

  View details for PubMedID 38831036

  View details for PubMedCentralID 3098534

• Near-atomic-resolution structure of J-aggregated helical light-harvesting nanotubes NATURE CHEMISTRY Deshmukh, A. P., Zheng, W., Chuang, C., Bailey, A. D., Williams, J. A., Sletten, E. M., Egelman, E. H., Caram, J. R. 2024

  Abstract

  Cryo-electron microscopy has delivered a resolution revolution for biological self-assemblies, yet only a handful of structures have been solved for synthetic supramolecular materials. Particularly for chromophore supramolecular aggregates, high-resolution structures are necessary for understanding and modulating the long-range excitonic coupling. Here, we present a 3.3 Å structure of prototypical biomimetic light-harvesting nanotubes derived from an amphiphilic cyanine dye (C8S3-Cl). Helical 3D reconstruction directly visualizes the chromophore packing that controls the excitonic properties. Our structure clearly shows a brick layer arrangement, revising the previously hypothesized herringbone arrangement. Furthermore, we identify a new non-biological supramolecular motif-interlocking sulfonates-that may be responsible for the slip-stacked packing and J-aggregate nature of the light-harvesting nanotubes. This work shows how independently obtained native-state structures complement photophysical measurements and will enable accurate understanding of (excitonic) structure-function properties, informing materials design for light-harvesting chromophore aggregates.

  View details for DOI 10.1038/s41557-023-01432-6

  View details for Web of Science ID 001156893700002

  View details for PubMedID 38316987

  View details for PubMedCentralID 2919932