Tailored Band Gaps in Sulfur‐ and Nitrogen‐Containing Porous Donor–Acceptor Polymers

Abstract

Donor-acceptor dyads hold the key to tuning of electrochemical properties and enhanced mobility of charge carriers, yet their incorporation into a heterogeneous polymer network proves difficulty owing to the fundamentally different chemistry of the donor and acceptor subunits. A family of sulfur- and nitrogen-containing porous polymers (SNPs) are obtained via Sonogashira-Hagihara cross-coupling and combine electron-withdrawing triazine (C N ) and electron-donating, sulfur-containing linkers. Choice of building blocks and synthetic conditions determines the optical band gap (from 1.67 to 2.58 eV) and nanoscale ordering of these microporous materials with BET surface areas of up to 545 m g and CO capacities up to 1.56 mmol g . Our results highlight the advantages of the modular design of SNPs, and one of the highest photocatalytic hydrogen evolution rates for a cross-linked polymer without Pt co-catalyst is attained (194 μmol h g ).

Exploring the “Goldilocks Zone” of Semiconducting Polymer Photocatalysts by Donor–Acceptor Interactions

“…[1] In photocatalytic water splitting, the ideal band gap has to straddle the proton reduction and the water oxidation potentials.I np ractice,o nly one half-reaction (proton reduction) occurs preferentially,b ecause the fourhole water oxidation is sluggish in comparison to spontaneous electron-hole recombination within the catalyst. [3] Synthetic strategies to narrow down the optical band gap of polymers commonly rely on sequential increases of the size of p-conjugated segments and hence,ared shift of the optical adsorption edge. [3] Synthetic strategies to narrow down the optical band gap of polymers commonly rely on sequential increases of the size of p-conjugated segments and hence,ared shift of the optical adsorption edge.…”

“…[2] Sacrificial electron donors,s uch as triethanolamine (TEOA), that have more negative potentials and require only two-hole oxidation are routinely employed, and experiments show that the optimal band gap for this redox system is 2.2-2.4 eV. [3] Synthetic strategies to narrow down the optical band gap of polymers commonly rely on sequential increases of the size of p-conjugated segments and hence,ared shift of the optical adsorption edge. [4] Fore xample,c onjugated microporous polymers (CMPs) are based on polycyclic, aromatic hydrocarbons of varying lengths, [5] and they have found applications in organic electronics as light emitters, [3a] polymer light emitting diodes (PLEDs), solar cells, [6] and as photocatalysts.…”

A π‐Conjugated, Covalent Phosphinine Framework

“…This is an extraordinarilyh ight hermal and oxidative stability,o utperforming any of the S-and N-containingp olymer frameworks. [9][10] The comprehensive structure characterization of CPF-1, as well as monomer 4 and PMC, demonstrates that a p-conjugated and stable phosphinine-based framework was successfully prepared, althoughs ome catalystr esidues remain trapped in the pore structure.…”

“…[12] Further, sulfur-and nitrogen-containingp olymers feature intimately linkedd onor-acceptor domains and an arrow band gap, which result in record-breaking performances in photocatalytic water splitting. [13] Despite the confusing threeletter nomenclature in this field, CTFs,C MPs, PAFs, and SNPs have chiefly in common that they are constructed from covalently linked p-conjugated buildingb locks; [1][2][3][9][10] electron delocalization in the polymer framework can improvet heir intriguing properties, especially electric storage and conductivity, band gap properties, photoluminescence, and light harvesting. [14] Strategies to expand the properties and applicationso f p-conjugated frameworks can be broadly divided into two categories;p ost-synthetic modifications and initialr eaction design.P ost-synthetic modifications rely on an umber of tools such as changes of the polymer topology (e.g.,b yt emplate removal, freeze-drying), [15] or various reactions that introduce heteroatoms into the backbone of the network.…”

“…[1-2, 7, 14, 17] Design of tectons is the most exciting and promisingf ield for further exploration, as hitherto only tectons containing the nonmetals C, N, O, and Sh ave been explored in anyd epth. [9][10]18] All main-group elements in the first three rows of the periodic table with four to six valence electrons can form aromatic rings. Lowers tability mayb et he reason why Si and P, which are light elements in the third period of the periodic table and in the same groups as Ca nd N, have never been introduced into p-conjugated frameworks.…”