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The novel photoswitchable ligand 3,3'‐Azobenz(metPA)2 (1) is used to prepare a [Cu2(1)2](BF4)2 metallocycle (2), whose photoisomerization was characterized using static and time‐resolved spectroscopic methods. Optical studies demonstrate the highly quantitative and reproducible photoinduced cyclic E/Z switching without decay of the complex. Accordingly and best to our knowledge, [Cu2(1)2](BF4)2 constitutes the first reversibly photoswitchable (3d)‐metallocycle based on azobenzene. The photoinduced multiexponential dynamics in the sub‐picosecond to few picosecond time domain of 1 and 2 have been assessed. These ultrafast dynamics as well as the yield of the respective photostationary state (PSSZ = 65 %) resemble the behavior of archetypical azobenzene. Also, the innovative pump‐probe laser technique of gas phase transient photodissociation (τ‐PD) in a mass spectrometric ion trap was used to determine the intrinsic relaxation dynamics for the isolated complex. These results are consistent with the results from femtosecond UV/Vis transient absorption (fs‐TA) in solution, emphasizing the azobenzene‐like dynamics of 2. This unique combination of fs‐TA and τ‐PD enables valuable insights into the prevailing interplay of dynamics and solvation. Both analyses (in solution and gas phase) and quantum chemical calculations reveal a negligible effect of the metal coordination on the switching mechanism and electronic pathway, which suggests a non‐cooperative isomerization process. [ABSTRACT FROM AUTHOR]

This article, titled "Cover Feature: A Photoswitchable Metallocycle Based on Azobenzene: Synthesis, Characterization, and Ultrafast Dynamics," highlights the discovery of an azobenzene-based metallocycle that can undergo reversible photoisomerization without disassembly. The cover feature showcases the switching between the (E,E) and (Z,Z) isomers of [Cu2(3,3'‐azobenz(metPA)2](BF4)2. The researchers used femtosecond UV/Vis transient absorption in solution and femtosecond pump-probe photodissociation in the gas phase to study the primary switching dynamics. For more information, readers can refer to the Research Article by C. Riehn, R. Diller, S. Becker, and their colleagues. [Extracted from the article]

Manganese complexes exhibit a rich redox chemistry, usually accompanied by structural reorganization during the redox processes often followed by ligand dissociation or association. The push–pull ligand 2,6-diguanidylpyridine (dgpy) stabilizes manganese in the oxidation states +II, +III, and + IV in the complexes [Mn-(dgpy)2]n+ (n = 2–4) without change in the coordination sphere in the condensed phase [Heinze et al., Inorganic Chemistry, 2022, 61, 14616]. In the condensed phase, the manganese-(IV) complex is a very strong oxidant. In the present work, we investigate the stability and redox activity of the MnIV complex and its counterion (PF6–) adducts in the gas phase, using two modified 3D Paul ion trap mass spectrometers. Six different cationic species of the type [Mnx(dgpy)2(PF6)y]n+ (x = II, III, IV, y = 0–3, n = 1–3) could be observed for the three oxidation states MnIV, MnIII, and MnII, of which one observed complex also contains a reduced dgpy ligand. MnII species showed the highest relative stability in collision induced dissociation and UV/vis photo dissociation experiments. The lowest stability is observed in the presence of one or more counterions, which correlates to a lower total charge n+. Gas phase UV/vis spectra show similar features as the condensed phase spectra only differing in relative band intensities. The strongly oxidizing MnIV complex reacts with triethylamine (NEt3) in the gas phase to give MnIII, while MnIII species show little reactivity toward NEt3. [ABSTRACT FROM AUTHOR]

The novel photoswitchable ligand 3,3'-Azobenz(metPA) 2 (1) is used to prepare a [Cu 2 (1) 2 ](BF 4 ) 2 metallocycle (2), whose photoisomerization was characterized using static and time-resolved spectroscopic methods. Optical studies demonstrate the highly quantitative and reproducible photoinduced cyclic E/Z switching without decay of the complex. Accordingly and best to our knowledge, [Cu 2 (1) 2 ](BF 4 ) 2 constitutes the first reversibly photoswitchable (3d)-metallocycle based on azobenzene. The photoinduced multiexponential dynamics in the sub-picosecond to few picosecond time domain of 1 and 2 have been assessed. These ultrafast dynamics as well as the yield of the respective photostationary state (PSS Z = 65 %) resemble the behavior of archetypical azobenzene. Also, the innovative pump-probe laser technique of gas phase transient photodissociation (τ-PD) in a mass spectrometric ion trap was used to determine the intrinsic relaxation dynamics for the isolated complex. These results are consistent with the results from femtosecond UV/Vis transient absorption (fs-TA) in solution, emphasizing the azobenzene-like dynamics of 2. This unique combination of fs-TA and τ-PD enables valuable insights into the prevailing interplay of dynamics and solvation. Both analyses (in solution and gas phase) and quantum chemical calculations reveal a negligible effect of the metal coordination on the switching mechanism and electronic pathway, which suggests a non-cooperative isomerization process., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)