Ehsan Hamzehpoor

• Ph.D.
• PhD Student at McGill University

Organic room-temperature phosphorescence, a spin-forbidden radiative process, has emerged as an interesting but rare phenomenon with multiple potential applications in optoelectronic devices, biosensing and anticounterfeiting. Covalent organic frameworks (COFs) with accessible nanoscale porosity and precisely engineered topology can offer unique be...

Two near‐infrared (NIR) emissive π‐conjugated covalent organic frameworks (COFs) pTANG1 and pTANG2 are synthesized using Knoevenagel condensation of trioxaazatriangulenetricarbaldehyde (TATANG) with benzene‐ and biphenyldiacetonitriles, respectively. The morphology of the COFs is affected by the size of TATANG precursor crystals. Donor–acceptor int...

We report a rapid, room‐temperature mechanochemical synthesis of 2‐ and 3‐dimensional boroxine covalent organic frameworks (COFs), enabled by using trimethylboroxine as a dehydrating additive to overcome the hydrolytic sensitivity of boroxine‐based COFs. The resulting COFs display high porosity and crystallinity, with COF‐102 being the first exampl...

We report a rapid, room‐temperature mechanochemical synthesis of 2‐ and 3‐dimensional boroxine covalent organic frameworks (COFs), enabled by using trimethylboroxine as a dehydrating additive to overcome the hydrolytic sensitivity of boroxine‐based COFs. The resulting COFs display high porosity and crystallinity, with COF‐102 being the first exampl...

Quantum dots (QDs) are promising building blocks for luminescent solar concentrators (LSCs), yet most QD‐based LSCs suffer from toxic metal composition and color tinting. UV‐selective harvesting QDs can enable visible transparency, but their development is restricted by large reabsorption losses and low photoluminescence quantum yield (PLQY). The d...

We report a rapid, room-temperature mechanochemical synthesis of 2- and 3-dimensional boroxine covalent organic frameworks (COFs), enabled by using trimethylboroxine as a dehydrating additive to overcome the hydrolytic sensitivity of boroxine-based COFs. The resulting COFs display high porosity and crystallinity, with COF-102 being the first exampl...

Carbon, although the central element in organic chemistry, has been traditionally neglected as a target for directional supramolecular interactions. The design of supramolecular structures involving carbon-rich molecules, such as arene...

It is hypothesized that during the periodate oxidation of bacterial cellulose (BC), the chains will be cleaved in the amorphous regions. Subsequent chlorite oxidation will cause highly charged cellulose chains on the outer surface of BC to go into solution and break up BC into smaller and thinner nanocellulose particles, to which the cleaved amorph...

2D materials with high charge carrier mobility and tunable electronic band gaps have attracted intense research effort for their potential use as active components in nanoelectronics. 2D-conjugated polymers (2DCP) constitute a promising sub-class due to the fact that the electronic band structure can be manipulated by varying the molecular building...

Thick‐shell colloidal quantum dots (QDs) are promising building blocks for solar technologies due to their size/composition/shape‐tunable properties. However, most well‐performed thick‐shell QDs suffer from frequent use of toxic metal elements including Pb and Cd, and inadequate light absorption in the visible and near‐infrared (NIR) region due to...

Recently, photochemistry of Electron Donor-Acceptor (EDA) complexes employing catalytic amounts of electron donors have become of interest as a new methodology in the catalysis field, allowing for decoupling of the electron transfer (ET) from the bond-forming event. However, examples of practical EDA systems in the catalytic regime remain scarce, a...

Luminescent solar concentrators (LSCs) constructed using colloidal quantum dots (QDs) have emerged as a promising and cost-effective solution for transparent photovoltaics. However, the efficiency of these LSCs in converting sunlight...

Organic room-temperature phosphorescence, a spin-forbidden radiative process, has emerged as an interesting but rare phenomenon with multiple potential applications in optoelectronic devices, biosensing, and anticounterfeiting. Covalent organic frameworks (COFs) with accessible nanoscale porosity and precisely engineered topology can offer unique b...

Two-dimensional (2D) π-conjugated polymers are promising electronic materials with diverse properties controlled by varying the structure of organic building blocks. We here report an organic framework with perchlorotriphenylmethyl (PTM) radical nodes, synthesized through dehalogenative thermolysis polymerization of tris(iodotetrachlorophenyl)metha...

Boroxine and dioxaborole are the first and some of the most studied synthons of Covalent Organic Frameworks (COFs). Despite their wide application in the design of functional COFs over the last 15 years, their synthesis still relies on the original Yaghi’s condensation of boronic acids (with itself or with polyfunctional catechols), some of which a...

We report a comparative study of two structurally similar donor-acceptor complexes with (1a) and without (2a) H-bonding using X-ray crystallography, spectroscopic analysis, and density functional theory calculations. H-Bonding enhances the donor-acceptor interactions, as manifested in a narrower band gap and shorter π-stacking distance in 1a versus...

We report a series of new halogenated bis(acenaphthylene)dione (BAN) derivatives and study the effect of their solid-state organization on optoelectronic properties and electron transport measured in n-type organic field-effect transistors...

Red luminescence is found in off‐white tris(iodoperchlorophenyl)methane (3I‐PTMH) crystals which is characterized by a high photoluminescence quantum yield (PLQY 91 %) and color purity (CIE coordinates 0.66, 0.34). The emission originates from the doublet excited state of the neutral radical 3I‐PTMR, which is spontaneously formed and becomes embedd...

Red luminescence in off‐white tris(iodoperchlorophenyl)methane crystals is characterized by a high quantum yield (PLQY 91 %) and color purity. The emission originates from the doublet excited state of the neutral radical defect. TD‐DFT calculations demonstrate that electron‐donating iodine atoms accelerate the radiative transition while the rigid h...

Molecular packing of organic luminogens governs their photophysical behavior. In their Communication (DOI: 10.1002/anie.201913393), E. Hamzehpoor and D. F. Perepichka report a series of highly emissive azatriangulenetrione (TANGO) solids whose luminescent properties are controlled by the size of substituents. The co‐alignment of carbonyl groups in...

Die Molekülpackung bestimmt das photophysikalische Verhalten organischer Luminogene. In ihrer Zuschrift (DOI: 10.1002/ange.201913393) berichten E. Hamzehpoor und D. F. Perepichka über eine Serie von Azatriangulentrionen (TANGO), deren Lumineszenzeigenschaften von der Größe der Substituenten abhängen. Die gleiche Ausrichtung der Carbonylgruppen in s...

High quantum yield luminescent organic solids are required for a number of optoelectronic applications, including organic light-emitting diodes (OLEDs) and transistors (OLETs), lasers, etc. The absolute majority of organic materials can only emit efficiently from their singlet excited states. Involving high-multiplicity states (such as triplets) in...

Nitro group (NO2) is one of the most common electron-withdrawing groups but it has rarely been used in the design of organic semiconductors (OSCs). Herein, we report n-type semiconducting behavior of simple fluorenone derivatives functionalized with NO2 and CN groups. While the electron mobilities measured in thin film field-effect transistors are...

The nitro group (NO2) is one of the most common electron-withdrawing groups but it has rarely been used in the design of organic semiconductors (OSCs). Herein, we report the n-type semiconducting behavior of simple fluorenone derivatives functionalized with NO2 and CN groups. While the electron mobilities measured in the thin film field-effect tran...

We report the first transformation between crystalline vinylene-linked two-dimensional (2D) polymers and crystalline cyclobutane-linked three-dimensional (3D) polymers. Specifically, absorption-edge irradiation of the 2D poly(arylenevinylene) covalent organic frameworks (COFs) results in topological [2+2] cycloaddition cross-linking the π-stacked l...

We report the first transformation between crystalline vinylene-linked two-dimensional (2D) polymers and crystalline cyclobutane-linked three-dimensional (3D) polymers. Specifically, absorption-edge irradiation of the 2D poly(arylenevinylene) covalent organic frameworks (COFs) results in topological [2+2] cycloaddition cross-linking the π-stacked l...

The black crystalline (aza)triangulene-based covalent organic framework (TANG-COF) was synthesized from trinitro-TANG precursor via one-pot-two-step reaction involving Pd-catalyzed hydrogenation and polycondensation with an aromatic dial-dehyde. High crystallinity and permanent porosity of the layered two-dimensional (2D) structure were established...

We report a series of highly emissive azatriangulenetrione (TANGO) solids in which the luminescent properties are controlled by engineering the molecular packing by adjusting the steric size of substituents. The co‐alignment of “phosphorogenic” carbonyl groups within the π‐stacks results in an almost pure triplet emission in HTANGO, TCTANGO, TBTANG...

We report a series of highly emissive azatriangulenetrione (TANGO) solids in which the luminescent properties are controlled by engineering the molecular packing by adjusting the steric size of substituents. The co‐alignment of ‘phosphorogenic’ carbonyl groups within the π‐stacks results in an almost pure triplet emission in HTANGO, TCTANGO, TBTANG...

The formation of ordered molecular structures on surfaces is determined by the balance between molecule-molecule and molecule-substrate interactions. Whether the aggregation process is guided by non-covalent forces or on-surface reactions, a deeper understanding of these interactions is pivotal to formulating a priori predictions of the final struc...

Designing structural order in electronically active organic solids remains a great challenge in the field of materials chemistry. Now, 2D poly(arylene vinylene)s prepared as highly crystalline covalent organic frameworks (COFs) by base‐catalyzed aldol condensation of trimethyltriazine with aromatic dialdehydes are reported. The synthesized polymers...

Kristalline zweidimensionale kovalente organische Gerüste (COFs) aus Polyarylenvinylenen wurden durch basenkatalysierte Aldolkondensation von Trimethyltriazin mit einer Serie von aromatischen Dialdehyden synthetisiert. Die erhaltenen COFs sind hydrolysestabil und hoch fluoreszierend (Quantenausbeute ≤50 %). Versetzen mit protischen Lösungsmitteln f...