Molecular Representations
Bar chart comparing SMILES-BERT accuracy against baselines on HIV, LogP, and PCBA tasks

SMILES-BERT: BERT-Style Pre-Training for Molecules

SMILES-BERT pre-trains a Transformer encoder on 18M+ SMILES from ZINC using a masked recovery task, then fine-tunes for molecular property prediction, outperforming prior methods on three datasets.

Predictive Chemistry
Bar chart comparing SMILES2Vec and Graph Conv scores across five MoleculeNet tasks

SMILES2Vec: Interpretable Chemical Property Prediction

SMILES2Vec is a deep RNN that learns chemical features directly from SMILES strings using a Bayesian-optimized CNN-GRU architecture. It matches graph convolution baselines on toxicity and activity prediction, and its explanation mask identifies chemically meaningful functional groups with 88% accuracy.

Molecular Representations
Visualization of tokenizer vocabulary coverage across chemical space

Smirk: Complete Tokenization for Molecular Models

Introduces Smirk and Smirk-GPE tokenizers that fully cover the OpenSMILES specification, proposes n-gram language models as low-cost proxies for evaluating tokenizer quality, and benchmarks 34 tokenizers across intrinsic and extrinsic metrics.

Molecular Representations
Bar chart showing SMILES Pair Encoding reduces mean sequence length from 40 to 6 tokens

SPE: Data-Driven SMILES Substructure Tokenization

Introduces SMILES Pair Encoding (SPE), a data-driven tokenization algorithm that learns high-frequency SMILES substrings from ChEMBL to produce shorter, chemically interpretable token sequences for deep learning.

Molecular Representations
Bar chart showing SPMM supports bidirectional tasks: molecule to property, property to molecule, molecule optimization, and property interpolation

SPMM: A Bidirectional Molecular Foundation Model

SPMM pre-trains a dual-stream transformer on SMILES and 53 molecular property vectors using contrastive learning and cross-attention, enabling bidirectional structure-property generation, property prediction, and reaction prediction through a single model.

Molecular Representations
Diagram showing the t-SMILES pipeline from molecular graph fragmentation to binary tree traversal producing a string representation

t-SMILES: Tree-Based Fragment Molecular Encoding

t-SMILES represents molecules by fragmenting them into substructures, building full binary trees, and traversing them breadth-first to produce SMILES-type strings that reduce nesting depth and outperform SMILES, DeepSMILES, and SELFIES on generation benchmarks.

Molecular Representations
Diagram showing sequence-to-sequence translation from chemical names to SMILES with atom count constraints

Transformer Name-to-SMILES with Atom Count Losses

This paper applies a Transformer sequence-to-sequence model to predict SMILES strings from chemical compound names (Synonyms). Two enhancements, an atom-count constraint loss and SMILES/InChI multi-task learning, improve F-measure over rule-based and vanilla Transformer baselines.

Predictive Chemistry
Bar chart comparing Transformer-CNN RMSE against RF, SVM, CNN, and CDDD baselines

Transformer-CNN: SMILES Embeddings for QSAR Modeling

Transformer-CNN extracts dynamic SMILES embeddings from a Transformer trained on SMILES canonicalization and feeds them to a TextCNN for QSAR modeling, achieving strong results across 18 benchmarks with built-in LRP interpretability.

Molecular Generation
Bar chart comparing Char-RNN and Molecular VAE on validity and novelty metrics

VAE for Automatic Chemical Design (2018 Seminal)

This foundational paper introduces a variational autoencoder (VAE) that encodes SMILES strings into a continuous latent space, allowing gradient-based optimization of molecular properties. Joint training with a property predictor organizes the latent space by chemical properties, and Bayesian optimization over the latent surface discovers drug-like molecules with improved QED and synthetic accessibility.

Molecular Representations
Horizontal bar chart showing X-MOL achieves best performance across five molecular tasks

X-MOL: Pre-training on 1.1B Molecules for SMILES

X-MOL applies large-scale Transformer pre-training on 1.1 billion molecules with a generative SMILES-to-SMILES strategy, then fine-tunes for five molecular analysis tasks including property prediction, reaction analysis, and de novo generation.

Molecular Generation
Diagram showing back translation workflow with forward and reverse models mapping between source and target molecular domains, augmented by unlabeled ZINC molecules

Back Translation for Semi-Supervised Molecule Generation

Adapts back translation from NLP to molecular generation, using unlabeled molecules from ZINC to create synthetic training pairs that improve property optimization and retrosynthesis prediction across Transformer and graph-based architectures.

Molecular Generation
Two Gaussian distributions in ChemNet activation space with the Frechet distance shown between them

Frechet ChemNet Distance for Molecular Generation

Introduces the Frechet ChemNet Distance (FCD), a single metric that captures chemical validity, biological relevance, and diversity of generated molecules by comparing distributions of learned ChemNet representations.