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oai:figshare.com:article/33990926 2026-09-24T21:05:04Z category_1 category_4 category_12 category_272 category_873 portal_63 item_type_3 month_year_09_2026

Dark- and Photoexcited-State Electronic Structures of [Ru(SO₂)(NH₃)₄X]Y Complexes and Their Relation to SO₂ Photoconversion Efficiency Haoqian Zhou (7496030) Jacqueline M. Cole (1301070) Biophysics Biochemistry Cell Biology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified rational molecular design quantum photosensing applications qualitatively similar across practical screening metric factors also contribute density analyses visualize 4 structural archetypes >- ligands control >- band center state projected densities high spatiotemporal precision >< sub >< pyridine (< b correspondingly higher pce ></ sub >-< 4 </ sub 2 </ sub 2 </ b state electronic structures >- ligand x 3 </ b >- ligand (< b state changes state behavior ></ sub yz </ trans </ p </ ligated structures crystal structures σ interactions yet available visible light varies markedly ten pyridyl study addresses structure calculations Single crystals of the [Ru(SO₂)(NH₃)₄X]Y family of complexes are promising photoswitches or photoactuators; they respond structurally to visible light, undergoing SO₂ linkage photoisomerization with high spatiotemporal precision. However, the SO₂ photoconversion efficiency (PCE) varies markedly with the <i>trans</i>-ligand X and no unifying molecular design principle is yet available. This study addresses this knowledge gap by performing electronic-structure calculations on 11 respective crystal structures of these complexes using reference crystal structures characterized by single-crystal X-ray diffraction under light irradiation. We focus on 4 structural archetypes of [Ru(SO₂)(NH₃)₄X][tosylate]₂, where X = H₂O (<b>1</b>), 3-F-pyridine (<b>2</b>), 3-Cl-pyridine (<b>3</b>), and 3-Br-pyridine (<b>4</b>), to elucidate how the <i>trans</i>-ligands control the Ru-centered electronic rearrangement upon photoexcitation. The dark-state projected densities of states of these crystal structures are qualitatively similar across the series, exhibiting [Ru]-S π-bonding and [Ru]-X π/σ interactions. By contrast, electronic-structure calculations using time-dependent density functional theory reveal distinct photoexcited-state behavior: in <b>1</b>, photoexcitation populates an antibonding <i>d</i>_<i>yz</i>-<i>p</i>_<i>y</i> orbital, weakening the [Ru]-S bond and lowering the SO₂ photoisomerization barrier; in <b>2</b>−<b>4</b>, photoexcitation simultaneously populates this antibonding orbital and depopulates its bonding counterpart, weakening the [Ru]-S bond substantially more to afford a correspondingly higher PCE than in <b>1</b>. Response charge-density analyses visualize the corresponding photoinduced charge redistribution in real space, consistent with the finer ordering of the PCE: <b>3</b> < <b>2</b> < <b>4</b>. We additionally propose the Ru <i>d</i>-band center as a descriptor for PCE: within a common class of <i>trans</i>-ligand, the PCE tends to decrease as the <i>d</i>-band center shifts toward the Fermi level, as shown here for ten pyridyl-ligated structures, although other factors also contribute to the photoisomerization process. Together, these results provide a mechanistic account of photoexcited-state changes in the electronic structure of [Ru(SO₂)(NH₃)₄X]Y complexes and suggest a practical screening metric for the rational molecular design of this family of high-PCE photoresponsive single crystals for quantum photosensing applications. 2026-09-24T00:00:00Z Dataset Dataset 10.1021/acs.jpclett.6c02623.s001 https://figshare.com/articles/dataset/Dark-_and_Photoexcited-State_Electronic_Structures_of_Ru_SO_sub_2_sub_NH_sub_3_sub_sub_4_sub_X_Y_Complexes_and_Their_Relation_to_SO_sub_2_sub_Photoconversion_Efficiency/33990926 CC BY-NC 4.0