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1. Chemiexcitation Acceleration of 1,2‐Dioxetanes by Spiro‐Fused Six‐Member Rings with Electron‐Withdrawing Motifs

   https://doi.org/10.1002/anie.202410057  

   David, Maya; Leirikh, Thomas; Shelef, Omri; Gutkin, Sara; Kopp, Tal; Zhou, Qingyang; Ma, Pengchen; Fridman, Micha; Houk, Kendall N; Shabat, Doron (November 2024, Angewandte Chemie International Edition)

   Abstract The chemiluminescent light‐emission pathway of phenoxy‐1,2‐dioxetane luminophores attracts growing interest within the scientific community. Dioxetane probes undergoing rapid flash‐type chemiexcitation exhibit higher detection sensitivity than those with a slow glow‐type chemiexcitation rate. We discovered that dioxetanes fused to non‐strained six‐member rings, with hetero atoms or inductive electron‐withdrawing groups, present both accelerated chemiexcitation rates and elevated chemical stability compared to dioxetanes fused to four‐member strained rings. DFT computational simulations supported the chemiexcitation acceleration observed by spiro‐fused six‐member rings with inductive electron‐withdrawing groups of dioxetanes. Specifically, a spiro‐dioxetane with a six‐member sulfone ring exhibited a chemiexcitation rate 293‐fold faster than that of spiro‐adamantyl‐dioxetane. A turn‐ON dioxetane probe for the detection of the enzyme β‐galactosidase, containing the six‐member sulfone unit, exhibited a S/N value of 108 in LB cell growth medium. This probe demonstrated a substantial increase in detection sensitivity towardsE. colibacterial cells expressing β‐galactosidase, with an LOD value that is 44‐fold more sensitive than that obtained by the adamantyl counterpart. The accelerated chemiexcitation and the elevated chemical stability presented by dioxetane containing a spiro‐fused six‐member ring with a sulfone inductive electron‐withdrawing group, make it an ideal candidate for designing efficient turn‐on chemiluminescent probes with exceptionally high detection sensitivity. 

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2. Crystal structure and photoreactivity of a halogen-bonded cocrystal based upon 1,2-diiodoperchlorobenzene and 1,2-bis(pyridin-4-yl)ethylene

   https://doi.org/10.1107/S2053229620006233  

   Bosch, Eric; Battle, Jessica D.; Groeneman, Ryan H. (June 2020, Acta Crystallographica Section C Structural Chemistry)

   null (Ed.)

   The formation of a photoreactive cocrystal based upon 1,2-diiodoperchlorobenzene ( 1,2-C 6 I 2 Cl 4 ) and trans -1,2-bis(pyridin-4-yl)ethylene ( BPE ) has been achieved. The resulting cocrystal, 2( 1,2-C 6 I 2 Cl 4 )·( BPE ) or C 6 Cl 4 I 2 ·0.5C 12 H 10 N 2 , comprises planar sheets of the components held together by the combination of I...N halogen bonds and halogen–halogen contacts. Notably, the 1,2-C 6 I 2 Cl 4 molecules π-stack in a homogeneous and face-to-face orientation that results in an infinite column of the halogen-bond donor. As a consequence of this stacking arrangement and I...N halogen bonds, molecules of BPE also stack in this type of pattern. In particular, neighbouring ethylene groups in BPE are found to be parallel and within the accepted distance for a photoreaction. Upon exposure to ultraviolet light, the cocrystal undergoes a solid-state [2 + 2] cycloaddition reaction that produces rctt -tetrakis(pyridin-4-yl)cyclobutane ( TPCB ) with an overall yield of 89%. A solvent-free approach utilizing dry vortex grinding of the components also resulted in a photoreactive material with a similar yield. 

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3. trans -Diamminebis(1,2-dicyanoethene-1,2-dithiolato)platinum(IV)

   https://doi.org/10.1107/S2414314620009803  

   Siddiqui, Mahaa J.; Nesterov, Volodymyr V.; Steidle, Matthew T.; Smucker, Bradley W. (July 2020, IUCrData)

   The title compound, [Pt(C 4 N 2 S 2 ) 2 (NH 3 ) 2 ], represents an octahedral platinum(IV) complex with two trans- ammine and two mnt (mnt = 1,2-dicyanoethene-1,2-dithiolato) ligands. The Pt—N and Pt—S distances are consistent with those in other platinum(IV) complexes. As a result of a slight canting of the coordination of the mnt ligand to the platinum(IV) atom, the nitrile nitrogen atoms are positioned suitably to hydrogen-bond with adjacent ammines. 

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4. Nickel‐Catalyzed 1,2‐Diarylation of Alkenyl Carboxylates: A Gateway to 1,2,3‐Trifunctionalized Building Blocks

   https://doi.org/10.1002/anie.201913062  

   Derosa, Joseph; Kang, Taeho; Tran, Van T.; Wisniewski, Steven R.; Karunananda, Malkanthi K.; Jankins, Tanner C.; Xu, Kane L.; Engle, Keary M. (December 2019, Angewandte Chemie International Edition)

   Abstract A nickel‐catalyzed conjunctive cross‐coupling of alkenyl carboxylic acids, aryl iodides, and aryl/alkenyl boronic esters is reported. The reaction delivers the desired 1,2‐diarylated and 1,2‐arylalkenylated products with excellent regiocontrol. To demonstrate the synthetic utility of the method, a representative product is prepared on gram scale and then diversified to eight 1,2,3‐trifunctionalized building blocks using two‐electron and one‐electron logic. Using this method, three routes toward bioactive molecules are improved in terms of yield and/or step count. This method represents the first example of catalytic 1,2‐diarylation of an alkene directed by a native carboxylate group. 

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5. A Diiron(I/II) μ-1,2-Carbonyl Complex Relevant to CO Binding on Fe(111)

   https://doi.org/10.1021/acs.inorgchem.5c00759  

   John, Titto Sunil; Singh, Devender; Maurel, Vincent; García-Serres, Ricardo; Murray, Leslie J (June 2025, Inorganic Chemistry)

   Fischer–Tropsch conversion of syngas to hydrocarbons is proposed to begin with CO binding to the iron surface of the catalyst. CO adsorption on various iron facets of relevance to the Fischer–Tropsch process suggest that the Fe(111) surface is the most active for catalysis, and that CO bound to the penultimate layer of Fe atoms or the b-state is the resting state during catalysis. Notably, a μ-1,2 mode was discarded for the b-state due to a lack of exemplar molecular species and expectation that such a mode would have a higher energy infrared (IR) absorption than observed experimentally (viz. 1735–1860 cm–1). Here, we report the synthesis of a diiron(I/II) complex in which CO binds μ-1,2: (Fe(OTf))(Fe(THF)(μ-1,2-CO))L where L2– is a bis(β-diketiminate) cyclophane (1). Surprisingly, the observed νCO at 1763 cm–1 for 1 compares well with that reported for b-state. Electron paramagnetic resonance (EPR), Mössbauer, and density functional theory (DFT) results support a weakly coupled s = 3/2 iron(I) and s = 2 iron(II) pair. Reduction of 1 results in C–O cleavage and C–C bond formation to yield a ketenylidene (CCO) complex as a major product observed spectroscopically. 

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