Room‐Temperature Linear Light Upconversion in a Mononuclear Erbium Molecular Complex

Abstract

To date,t he piling up of successive photons of low energies (near infrared;N IR) using as ingle lanthanide center and linear optics to ultimately produce upconverted visible emission was restricted to low-phonon solid materials and nanoparticles.Now we show that the tight helical wrapping of three terdentate N-donor ligands around as ingle nine-coordinate trivalent erbium cation provides favorable conditions for am ononuclear molecular complex to exhibit unprecedented related upconverted emission. Low power NIR laser excitations into the metal-centered transitions Er( 4 I 11/2 ! 4 I 15/2 ) at 801 nm or Er( 4 I 13/2 ! 4 I 15/2 )a t966nmr esult in upconverted blue-green emissions,where two or three photonsrespectively are successively absorbed by am olecular lanthanide complex possessing high-energy vibrations.

NIR‐NIR‐Aufkonvertierung in molekularen Chrom‐Ytterbium‐Salzen

“…[4] In den letzten Jahren konnten viele Fortschritte bei der Erweiterung von metallbasierter UC auf molekulare Komplexverbindungen erzielt werden, teilweise sogar bei Raumtemperatur und in Lçsung. [5] Beispielsweise konnte dies in Kombinationen aus Metallkomplexen und organischen Chromophoren, [6] in einkernigen Metallkomplexen [7] und in heterooligometallischen Sensibilisator-Aktivator-Architekturen erreicht werden. [8,9] Letztere zeigten das grçßte Potential füreffiziente UC,h auptsächlich fürE nergietransfer-Aufkonvertierung (ETU), aber auch fürk ooperativ sensibilisierte Aufkonvertierung (CSU).…”

Near‐IR to Near‐IR Upconversion Luminescence in Molecular Chromium Ytterbium Salts

“…[4] In the past few years,h owever, many advances have been achieved in implementing metal-based UC in molecular complex species, some even at ambient temperature and in solution. [5] This includes metal chelate-organic chromophore combinations, [6] mononuclear metal complexes, [7] and hetero-oligometallic sensitizer-activator architectures. [8,9] Thelatter have shown to hold the greatest potential for efficient UC,e specially for energy transfer upconversion (ETU) but also for cooperatively sensitized upconversion (CSU).…”

Room-Temperature Upconversion in a Nanosized {Ln15} Molecular Cluster-Aggregate

“…To achieve this, the authors performed a double-selective excitation using two pulsed lasers with the suitable required energy. This significant advancement in this field led to further development of molecular UC systems pioneered by Piguet, Charbonnière, and co-workers. − These seminal works led to a better understanding of the UC process in molecular systems. More specifically, the ETU mechanism in heteropolynuclear assemblies, the occurrence of competition between multicenter ETU and single-center ESA mechanisms and pure ESA mechanism in triple helical mononuclear complexes .…”

“…More specifically, the ETU mechanism in heteropolynuclear assemblies, the occurrence of competition between multicenter ETU and single-center ESA mechanisms and pure ESA mechanism in triple helical mononuclear complexes . With that said, it is well understood that molecule-based UC signals are weak; thus estimations of quantum yields and excited-state lifetimes are not reliable . Consequently, to take advantage of molecular UC for practical applications, a lot more remains to be accomplished to increase the emission intensity and quantum yield and reduce the required laser power to observe UC in molecular species.…”

“…15 With that said, it is well understood that molecule-based UC signals are weak; thus estimations of quantum yields and excited-state lifetimes are not reliable. 14 Consequently, to take advantage of molecular UC for practical applications, a lot more remains to be accomplished to increase the emission intensity and quantum yield and reduce the required laser power to observe UC in molecular species.…”