skip to main content

Attention:

The NSF Public Access Repository (NSF-PAR) system and access will be unavailable from 11:00 PM ET on Friday, September 13 until 2:00 AM ET on Saturday, September 14 due to maintenance. We apologize for the inconvenience.


This content will become publicly available on May 22, 2025

Title: Reversible Photochromism of 4,4’‐Disubstituted 2,2’‐Bipyridine in the Presence of SO 3
Abstract

We report an unusual photochromic behavior of 4,4′‐disubstituted‐2,2′‐bipyridine. It was found that in the presence of a SO3source and HCl, 2,2′‐bipyridine‐4,4′‐dibutyl ester undergoes a color change from yellow to magenta in solution with maximum absorbance at 545 nm upon irradiation with 395 nm light. The photochromism is thermally reversible in solution. Different from the known bipyridine‐based photoswitching pathways, the photo response does not involve any metal which form colored complexes or the formation of colored free radical cations like the photo‐reduction of viologens. A combination of experimental and computational analysis was used to probe the mechanism. The results suggest the colored species to be a complex formed between N‐oxide of the 2,2′‐bipyridine‐4,4′‐dibutyl ester and SO2; the N‐oxide and SO2are formed from photoactivated oxidation of the bipyridine with SO3serving as the oxygen source. This complex represents a new addition to the library of photoswitches that is easy to synthesize, reversible in solution, and of high fatigue resistance, making it a promising candidate for applications in photo‐switchable materials and SO3detection. We also demonstrated experimentally similar photochromic behaviors with 2,2’‐bipyridine‐containing polymers.

 
more » « less
Award ID(s):
2238935
NSF-PAR ID:
10522522
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
ChemPhysChem
Volume:
25
Issue:
17
ISSN:
1439-4235
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    We report the hydrothermal syntheses and crystal structures of aquabis(2,2′-bipyridine-κ 2 N , N ′)copper(II) hexafluoridosilicate tetrahydrate, [Cu(bpy) 2 (H 2 O)][SiF 6 ]·4H 2 O (bpy is 2,2′-bipyridine, C 10 H 8 N 2 ), (I), bis(2,2′-bipyridine-3κ 2 N , N ′)-di-μ-fluorido-1:3κ 2 F : F ;2:3κ 2 F : F -decafluorido-1κ 5 F ,2κ 5 F -ditantalum(V)copper(II), [Cu(bpy) 2 (TaF 6 ) 2 ], (II), tris(2,2′-bipyridine-κ 2 N , N ′)copper(II) bis[hexafluoridotantalate(V)], [Cu(bpy) 3 ][TaF 6 ] 2 , (III), and catena -poly[[diaqua(2,2′-bipyridine-κ 2 N , N ′)copper(II)]-μ-fluorido-tetrafluoridotin-μ-fluorido], [Cu(bpy)(H 2 O) 2 SnF 6 ] n , (IV). Compounds (I), (II) and (III) contain locally chiral copper coordination complexes with C 2 , D 2 , and D 3 symmetry, respectively. The extended structures of (I) and (IV) are consolidated by O—H...F and O—H...O hydrogen bonds. The structure of (III) was found to be a merohedral (racemic) twin. 
    more » « less
  2. Abstract

    A bis(pyrazolylpyridyl) ligand, L, containing a central photochromic dithienylethene spacer predictably forms a ferrous [Fe2L3]4+helicate exhibiting spin crossover (SCO). In solution, the compound [Fe2L3](ClO4)4(1) preserves the magnetic properties and is fluorescent. The structure of1is photo‐switchable following the reversible ring closure/opening of the central dithienylethene via irradiation with UV/visible light. This photoisomerization switches on and off some emission bands of1and provides a means of externally manipulating the magnetic properties of the assembly.

     
    more » « less
  3. Abstract

    A bis(pyrazolylpyridyl) ligand, L, containing a central photochromic dithienylethene spacer predictably forms a ferrous [Fe2L3]4+helicate exhibiting spin crossover (SCO). In solution, the compound [Fe2L3](ClO4)4(1) preserves the magnetic properties and is fluorescent. The structure of1is photo‐switchable following the reversible ring closure/opening of the central dithienylethene via irradiation with UV/visible light. This photoisomerization switches on and off some emission bands of1and provides a means of externally manipulating the magnetic properties of the assembly.

     
    more » « less
  4. Abstract

    We report the design of a bifunctional metal–organic layer (MOL), Hf12‐Ru‐Co, composed of [Ru(DBB)(bpy)2]2+[DBB‐Ru, DBB=4,4′‐di(4‐benzoato)‐2,2′‐bipyridine; bpy=2,2′‐bipyridine] connecting ligand as a photosensitizer and Co(dmgH)2(PPA)Cl (PPA‐Co, dmgH=dimethylglyoxime; PPA=4‐pyridinepropionic acid) on the Hf12secondary building unit (SBU) as a hydrogen‐transfer catalyst. Hf12‐Ru‐Co efficiently catalyzed acceptorless dehydrogenation of indolines and tetrahydroquinolines to afford indoles and quinolones. We extended this strategy to prepare Hf12‐Ru‐Co‐OTf MOL with a [Ru(DBB)(bpy)2]2+photosensitizer and Hf12SBU capped with triflate as strong Lewis acids and PPA‐Co as a hydrogen transfer catalyst. With three synergistic active sites, Hf12‐Ru‐Co‐OTf competently catalyzed dehydrogenative tandem transformations of indolines with alkenes or aldehydes to afford 3‐alkylindoles and bisindolylmethanes with turnover numbers of up to 500 and 460, respectively, illustrating the potential use of MOLs in constructing novel multifunctional heterogeneous catalysts.

     
    more » « less
  5. Abstract

    We report the design of a bifunctional metal–organic layer (MOL), Hf12‐Ru‐Co, composed of [Ru(DBB)(bpy)2]2+[DBB‐Ru, DBB=4,4′‐di(4‐benzoato)‐2,2′‐bipyridine; bpy=2,2′‐bipyridine] connecting ligand as a photosensitizer and Co(dmgH)2(PPA)Cl (PPA‐Co, dmgH=dimethylglyoxime; PPA=4‐pyridinepropionic acid) on the Hf12secondary building unit (SBU) as a hydrogen‐transfer catalyst. Hf12‐Ru‐Co efficiently catalyzed acceptorless dehydrogenation of indolines and tetrahydroquinolines to afford indoles and quinolones. We extended this strategy to prepare Hf12‐Ru‐Co‐OTf MOL with a [Ru(DBB)(bpy)2]2+photosensitizer and Hf12SBU capped with triflate as strong Lewis acids and PPA‐Co as a hydrogen transfer catalyst. With three synergistic active sites, Hf12‐Ru‐Co‐OTf competently catalyzed dehydrogenative tandem transformations of indolines with alkenes or aldehydes to afford 3‐alkylindoles and bisindolylmethanes with turnover numbers of up to 500 and 460, respectively, illustrating the potential use of MOLs in constructing novel multifunctional heterogeneous catalysts.

     
    more » « less