Mechanistic Investigations of Organic Aggregates with Different Topologies for Optical Limiting Applications

Linear and Nonlinear Optical Properties of Natural Dyes Freestanding Films and Application in Optical Limiting

10.32792/utq/utjsci/vol7/2/30 ◽

2020 ◽

pp. 139-143

Keyword(s):

Absorption Coefficient ◽

Water Solution ◽

Optical Limiting ◽

Refraction Index ◽

Laser Wavelength ◽

Solid State Laser ◽

Natural Dyes ◽

Linear And Nonlinear ◽

532 Nm ◽

Absorbance Spectra

Natural dyes were followed and prepared from a pomegranate, purple carrot, and eggplant peel. The absorbance spectra was measured in the wavelength range 300-800 nm. The linear properties measurements of the prepared natural dye freestanding films were determined include absorption coefficient (α0), extinction coefficient (κ), and linear refraction index (n). The nonlinear refractive index n2 and nonlinear absorption coefficient β2 of the natural dyes in the water solution were measured by the optical z-scan technique under a pumped solid state laser at a laser wavelength of 532 nm. The results indicated that the pomegranate dye can be promising candidates for optical limiting applications with significantly low optical limiting of 3.5 mW.

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Three-Component [1+1+1] Cyclopropanation with Ruthenium(II)

10.26434/chemrxiv.6025772 ◽

2018 ◽

Author(s):

Tanner C. Jankins ◽

Robert R. Fayzullin ◽

Eugene Khaskin

Keyword(s):

Quaternary Carbon ◽

Poor Control ◽

One Step ◽

Synthetic Routes ◽

Mechanistic Investigations ◽

Chiral Centers ◽

Metal Catalyzed ◽

The Right ◽

Substituted Cyclopropanes

We report a one-step, Ru(II)-catalyzed cyclopropanation reaction that is conceptually different from the previously reported protocols that include Corey-Chaykovsky, Simmons-Smith, and metal catalyzed carbene attack on olefins. Under the current protocol, various alcohols are transformed into sulfone substituted cyclopropanes with excellent isolated yields and diastereoselectivities. This new reaction forms highly congested cyclopropane products with three new C–C bonds, three or two new chiral centers and one new quaternary carbon center. 22 examples of isolated substrates are given. Previously reported synthetic routes for similar substrates are all multi-step, linear routes that proceed with overall low yields and poor control of stereochemistry. Experimental mechanistic investigations suggest initial metal-catalyzed dehydrogenation of the alcohol substrate and catalyst independent stepwise attack of two equivalents of sulfone on the aldehyde under basic conditions. While the Ru(II) is only responsible for the initial dehydrogenation step, the rate of aldehyde formation is crucial to maintaining the right balance of intermediates needed to afford the cyclopropane product.

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Visible Light-Induced Sulfonylation/Arylation of Styrenes in a Double Radical Three-Component Photoredox Reaction

10.26434/chemrxiv.7722020.v1 ◽

2019 ◽

Author(s):

Benjamin Lipp ◽

Lisa Marie Kammer ◽

Murat Kucukdisli ◽

Adriana Luque ◽

Jonas Kühlborn ◽

...

Keyword(s):

Visible Light ◽

Radical Formation ◽

Three Component Reaction ◽

Broad Variety ◽

Styrene Derivatives ◽

Mechanistic Investigations

Simultaneous sulfonylation/arylation of styrene derivatives is achieved in a photoredox-catalyzed three-component reaction using visible light. A broad variety of difunctionalized products is accessible in mostly excellent yields and high diastereoselectivity. The developed reaction is scalable and suitable for the modification of styrene-functionalized biomolecules. Mechanistic investigations suggest the transformation to be operating through a designed sequence of radical formation and radical combination.<br>

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