A Miniaturized Linear pH Sensor Based on a Highly Photoluminescent Self‐Assembled Europium(III) Metal–Organic Framework

Small but important: A miniaturized prototype for pH sensing in the pH range 5–7.5 has been constructed from a photoluminescent Eu3+ metal–organic framework that contains two different Eu3+ sites (Eu1 and Eu2; see picture) and self-assembles through hydrogen bonding and π–π interactions. This material has a very high quantum yield and an excellent balance between absorption, energy transfer, and emission rate.