The Interplay of Nanoconfinement and pH from the Perspective of a Dye‐Reporter Molecule. Issue 12 (23rd October 2020)

• Record Type: Journal Article
• Authors: Brilmayer, Robert; Brodrecht, Martin; Kaiser, Christoph; Breitzke, Hergen; Kumari, Bharti; Wachtveitl, Josef; Buntkowsky, Gerd; Andrieu‐Brunsen, Annette
• Is Part Of: ChemNanoMat. Volume 6:Issue 12(2020)
• Page Start: 1843
• Page End: 1853
• Publication Date: 2020-10-23
• Subjects: fluorescence dye -- ratiometric -- silica -- mesopore -- solid-state NMR; Nanochemistry -- Periodicals; Nanostructured materials -- Periodicals; Nanochemistry; Nanostructured materials; Periodicals; 541.2
• DOI: 10.1002/cnma.202000423
• Languages: English
• ISSNs: 2199-692X

Abstract

Abstract: A novel thiazol‐based ratiometric dye for the detection of local pH values is synthesized, and its properties are characterized by a combination of optical spectroscopy, solid‐state NMR and DNP (dynamic nuclear polarization)‐enhanced solid‐state NMR. This novel dye covers a completely different sensitivity range with its acidic pKa value of 3.5 compared to other established dyes for ratiometric pH detection, such as SNARF. The dye is grafted to the surfaces of mesoporous silica materials, which enables, for the first time, direct in situ measurements of the local pH values in silica mesopores by a simple UV‐vis spectroscopy method. The obtained results, which are in good agreement with previous indirect techniques, indicate a background electrolyte‐dependent pKa shift of at least one pH unit under nanoconfined conditions compared to the pKa of the dye in bulk solution. Abstract : A new ratiometric thiazol‐based dye (MPT−Ph) for pH detection in silica mesopores is presented, and its properties are characterized by optical spectroscopy, solid‐state NMR and DNP‐enhanced solid‐state NMR. Direct in situ measurements of the local apparent pH value in silica mesopores by a simple UV‐vis spectroscopy method are presented. The results enable direct measurements of nanoconfinement‐induced pKa shifts and prove the apparent pH shifts of at least one pH unit.