Thermochromic Color Switching to Temperature Controlled Volatile Memory and Counter Operations with Metal–organic Complexes and Hybrid Gels

Abstract

Temperature is often not considered as a precision stimulus for artificial chemical systems in contrast to the host–guest interactions related to many natural processes. Similarly, mimicking multi‐state volatile memory operations using a single molecular system with temperature as a precision stimulus is highly laborious. Here we demonstrate how a mixture of iron(II) chloride and bipyridine can be used as a reversible color‐to‐colorless thermochromic switch and logic operators. The generality of the approach was illustrated using CoII and NiII salts that resulted in color‐to‐color transitions. DMSO gels of these systems, exhibited reversible opaque‐transparency switching. More importantly, optically readable multi‐state volatile memory with temperature as a precision input has been demonstrated. The stored data is volatile and is lost instantaneously upon withdrawal or change of temperature. Simultaneous read‐out at multiple wavelengths results in single‐input/multi‐output sequential logic operations such as data accumulators (counters) leading to volatile memory states. The present system provides access to thermoresponsive materials wherein temperature can be used as a precision stimulus.