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.