Major Challenges for the Modern Chemistry in Particular and Science in General

Abstract

In the past few hundred years, science has exerted an enormous influence on the way the world appears to human observers. Despite phenomenal accomplishments of science, science nowadays faces numerous challenges that threaten its continued success. As scientific inventions become embedded within human societies, the challenges are further multiplied. In this critical review, some of the critical challenges for the field of modern chemistry are discussed, including: (a) interlinking theoretical knowledge and experimental approaches; (b) implementing the principles of sustainability at the roots of the chemical design; (c) defining science from a philosophical perspective that acknowledges both pragmatic and realistic aspects thereof; (d) instigating interdisciplinary research; (e) learning to recognize and appreciate the aesthetic aspects of scientific knowledge and methodology, and promote truly inspiring education in chemistry. In the conclusion, I recapitulate that the evolution of human knowledge inherently depends upon our ability to adopt creative problem-solving attitudes, and that challenges will always be present within the scope of scientific interests.

Keywords: Philosophy of Chemistry; Pragmatism; Reductionism; Sustainability; Systems science.

Fig. 1

Potential energy, obtained as a sum of the attractive and repulsive terms from the DLVO theory, represented as a function of the interparticle distance (left). Note that thermal energy of the system, kT, needs to be significantly smaller comparing to V_max in order for its stability to be preserved. If secondary energy minimum, V_sec, is not sufficiently higher than kT, a weak flocculation in this secondary minimum normally occurs. This curve neatly corresponds to the concept of intermolecular potential first proposed in the given form (right) by Rudjer Boškovíc in the mid-18th century. Albeit entirely qualitative, his theory is nowadays acknowledged as the cornerstone of the modern theory of atomic forces. Both theories employ the same fundamental concept: explaining the properties of matter through the interplay between attractive and repulsive forces. Reprinted with permission from Ref. Tirrell and Katz 2005

Fig. 2

Qualities ascribed to each natural system are the product of its interaction with a given physical context. Both the physical context and the inner organization of the system are involved in the definition of its qualities. In this drawing, the lines of interaction figuring at the boundary between the system and its environment present the reflections of the system’s qualities

Fig. 3

All atomic constituents of life—such as carbon, nitrogen and water depicted hereby—continually circle between biological, mineral, soil and atmospheric bodies of the planet. What is released as a waste by one species becomes absorbed as a nutrient by others, and industrial networks should certainly pursue the same zero-waste ideal in their future development. This is why it has been said that cities, and not rain forests, should become the mines for the “virgin” materials in the future (Gardner and Sampat 1998). However, whenever the waste is inherently non-recyclable, such as nuclear waste, or dissipates during usage with environmentally harmful consequences, as in the case of detergents, paints, chlorofluorocarbons in refrigerators and the most of industrially employed heavy metals, green alternatives at the stage of chemical synthesis should be looked for

Fig. 4

AFM micrographs of amelogenin particles appearing as triangularly shaped (left) or spherical (right), depending on the AFM tip shape. Morphology of the tip shape apparently becomes reflected in the observed morphology of amelogenin particles. Notice how below the dolphin-shaped vacuity on the right image the retraced tip starts producing similar artifacts as on the left image and eventually loses the contact with the surface. After a correction of the pressing force, the image restores its “faithful” representation of the surface morphology

Fig. 5

The concept of zeta-potential (left) presents a standard explanatory tool in colloid chemistry, though occasional attraction between similarly charged species stands as en enigmatic phenomenon from its standpoint. Electron micrograph showing negatively charged nanosized gold particles adsorbed on electronegative plate-shaped kaolin crystals (right). Although kaolin platelets are negatively charged as a whole, their edges are electropositive and as such attract the gold particles onto them. Reprinted with permission from Ref. Uskokovíc (2009a)

Fig. 6

According to the key-and-lock metaphor of the host-guest catalytic interactions in biochemistry (scheme above), the molecular recognition effect occurs when the shape of the substrate fits the one of the enzyme. A less oversimplified model (scheme below) takes into account the conformational adjusting of the enzyme to facilitate this interaction. In some cases the substrate molecules also modify their tertiary structure as they enter the active site of catalysis, indicating that mutual changes of the interacting entities condition most, if not all, chemical modifications in Nature. It is, however, required for any more realistic depiction to refer to subtle conformational changes and physicochemical forces taking place at the atomic size scale. Note also that despite more than half a century of detailed investigations of protein structure and function, there are many open questions and a generalized theory describing the precise physical origins of enzymatic catalysis is still lacking (Gärtner 2009; Martí et al. 2004, 2008)

Fig. 7

Versatile concepts used to explain the behavior of water at different scales (top). Notice how changes in the size of water aggregates instigate different scientific fields to get involved in predicting its physical transformations. Other physical contexts, such as biological, nutritional or agricultural, are tied with investigating the role and behavior of water from additional specific perspectives. The presented hierarchy of water models (bottom) in the theoretical analysis of physicochemical phenomena signifies how computational costs increase in parallel with the increase in the modeling resolution

Fig. 8

A typical Gaussian interrelation between the intensities of incoming and outgoing signals in a spectrometric analysis. Note that the optimum set of conditions for measurements aimed to attain the best possible resolution sacrifices both the area of maximal sensitivity and the area of maximal intensity, and instead finds the way between. Thus, among many other balances that science implicitly teaches us, the one between sensitivity and powerfulness occupies an important place in each experimental observation

Fig. 9

Different vibrational spectra of water in bulk conditions (left), and in droplets of 2.5 (middle) and 7.5 nanometers (right) in size. Many properties of water including diffusivity, viscosity, dielectric permittivity, polarity and acidification gradients have been shown to change depending on the size of aqueous droplets, implying that different environmental contexts trigger different physicochemical behavior of water confined to nanosized spaces, such as in biological environments. Reprinted with permission from Ref. Crupi et al. 2007

Fig. 10

The active site of arabinose binding protein with the essential structural role of hydrogen bonds and water molecules (left), and water molecules depicted as V-shaped entities playing a similarly active role in the binding site of oligopeptide binding protein (right). Even though molecular biologists have traditionally drawn their models against uniformly colored backgrounds, the scientific understanding is nowadays getting in line with Paracelsus’ conception that “water is the matrix of the world and all of its creatures”, in which an active role of water is implicitly acknowledged. The active volume of macromolecules is thus, more and more, drawn so as to extend beyond its formal boundaries, although at the cost of limiting the timescales and conformational spaces that can be assessed in molecular dynamics simulations. As Philip Ball, a co-editor of Nature magazine, asserts, “the structure and dynamics of this hydration shell seem to feed back onto those aspects of the protein themselves so that biological function depends on a delicate interplay between what we have previously regarded as distinct entities: the molecule and its environment”. The fact that the hydrogen-bonded network in the hydration layer of a peptide molecule or water dynamics in the cellular environment are different in comparison with those of bulk water, clearly indicates a feedback, co-assembly interaction possibly within every “self-assembly” process in Nature. The question of where the system ends and where the environment begins will turn out to be increasingly crucial and harder to define as the experimental settings and human interference with physical systems become more complex and sensitive. Reprinted with permission from Ref. Whitehead (1928)

Fig. 11

The essential concept of statistical thermodynamics is that the probability of finding the system in a given state can be represented as the product of two separate probability terms: a Boltzmann factor, according to which the higher the energy of the state, the less probable it is; and b degeneracy factor, according to which the higher the energy of the state, the more ways there is by which that state could be reached, and therefore the higher the probability of settling of the system into that state would be. As a result, the most probable state of the system does not correspond to the lowest energetic state, but there is a finite width of energy probability distribution peaking at energies above the ground level (Cooper 1999)

Fig. 12

Aragonite crystals obtained: by the reaction between calcium chloride and urea at 90°C (left); by the same reaction carried out in magnetic stirring conditions (middle); by preheating the precursor solutions to 90°C and then rapidly mixing them (right). Reprinted with permission from Ref. Wang et al. 1999

Fig. 13

Ever since Isaac Newton wrote that “I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me” (Brewster 1885), the metaphor of the coast of solid knowledge and the ocean of unknown meeting at the seashore of human mind has been one of the most beautiful ones in depicting the quest for knowledge. The current interest for nanoscale physical phenomena presents a natural consequence of the continually improving scientific mastery of “playing” with the planetary matter at ever smaller size scales. This is why a boy facing downward while being immersed in the beauty and secret meanings of small and negligible seashore pebbles may present a symbol of the curiosity that drives the voyage towards new discoveries in the field of nanosciences and nanotechnologies

Fig. 14

Morse curve representing the potential energy of an anharmonic oscillator as a function of distance between the oscillating entities (the scale herein corresponds to atoms in a hydrogen molecule). Had the shape of this curve been symmetrical (i.e. harmonic oscillator), numerous effects, including the finite thermal conductance of solid bodies, thermal expansion, molecular dissociation and the appearance of combination bands and overtones, could not have been explained