A new microporous Zr ⁴⁺ MOF combines both extraordinary sorption capability and exceptional luminescence sensing properties for Cr( vi ) in aqueous media.

We report an anion exchange composite material based on a protonated amine-functionalized metal–organic framework, denoted Metal Organic Resin-1 (MOR-1), and alginic acid (HA). MOR-1–HA material shows an exceptional capability to rapidly and selectively sorb Cr(VI) under a variety of conditions and in the presence of several competitive ions. The selectivity of MOR-1–HA for Cr(VI) is shown to be the result of strong O₃Cr^VI⋯NH₂ interactions. The composite sorbent can be successfully utilized in an ion-exchange column, in contrast to pristine MOR-1 which forms fine suspensions in water passing through the column. Remarkably, an ion exchange column with only 1% wt MOR-1–HA and 99% wt sand (an inert and inexpensive material) is capable of reducing moderate and trace Cr(VI) concentrations to well below the acceptable safety limits for water. The relatively low cost of MOR-1–HA/sand column and its high regeneration capability and reusability make it particularly attractive for application in the remediation of Cr(VI)-bearing industrial waste.

In this review we approach the emerging field of sensors based on luminescent metal–organic frameworks from the perspective of the most commonly encountered pitfalls and we suggest best practices so that they can be avoided.